Can't understand the Beta distribution as described in this paper

Question

I'm reading through the following paper (1). On page 2, section 2.1, there's a description of the selection of a beta distribution used:

Since both the choice of s and the strategy for handling the case that all values are above the threshold affect the result, we propose to abandon the use of a single absolute threshold and instead use a prior parameter distribution S given by P(si), where si , i = 1, . . . , N are possible thresholds. We use thresholds ranging from 0.01 to unity in steps of 0.01, i.e. N = 100. The distributions used in our experiments are Beta distributions with means 0.1, 0.15, 0.2 (α = 1 and β = 18, 11 + 1/3, 8) as shown in Fig 2

Here's fig 2:

I think I understand the purpose - each of those 0.1, 0.15, 0.2 are the "important" value of the threshold, so I want the beta distribution to be highest at those increments, but I also want to test all values in the range 0.01-1.0 with a peak/mean at 0.1 or 0.15 or 0.2.

In the code (3), there are some beta distributions as hardcoded arrays of 100 values:

static float betaDist1[100] = {0.028911,0.048656,0.061306,0.068539,0.071703,0.071877,0.069915,0.066489,0.062117,0.057199,0.052034,0.046844,0.041786,0.036971,0.032470,0.028323,0.024549,0.021153,0.018124,0.015446,0.013096,0.011048,0.009275,0.007750,0.006445,0.005336,0.004397,0.003606,0.002945,0.002394,0.001937,0.001560,0.001250,0.000998,0.000792,0.000626,0.000492,0.000385,0.000300,0.000232,0.000179,0.000137,0.000104,0.000079,0.000060,0.000045,0.000033,0.000024,0.000018,0.000013,0.000009,0.000007,0.000005,0.000003,0.000002,0.000002,0.000001,0.000001,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000};

static float betaDist2[100] = {0.012614,0.022715,0.030646,0.036712,0.041184,0.044301,0.046277,0.047298,0.047528,0.047110,0.046171,0.044817,0.043144,0.041231,0.039147,0.036950,0.034690,0.032406,0.030133,0.027898,0.025722,0.023624,0.021614,0.019704,0.017900,0.016205,0.014621,0.013148,0.011785,0.010530,0.009377,0.008324,0.007366,0.006497,0.005712,0.005005,0.004372,0.003806,0.003302,0.002855,0.002460,0.002112,0.001806,0.001539,0.001307,0.001105,0.000931,0.000781,0.000652,0.000542,0.000449,0.000370,0.000303,0.000247,0.000201,0.000162,0.000130,0.000104,0.000082,0.000065,0.000051,0.000039,0.000030,0.000023,0.000018,0.000013,0.000010,0.000007,0.000005,0.000004,0.000003,0.000002,0.000001,0.000001,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000};

static float betaDist3[100] = {0.006715,0.012509,0.017463,0.021655,0.025155,0.028031,0.030344,0.032151,0.033506,0.034458,0.035052,0.035331,0.035332,0.035092,0.034643,0.034015,0.033234,0.032327,0.031314,0.030217,0.029054,0.027841,0.026592,0.025322,0.024042,0.022761,0.021489,0.020234,0.019002,0.017799,0.016630,0.015499,0.014409,0.013362,0.012361,0.011407,0.010500,0.009641,0.008830,0.008067,0.007351,0.006681,0.006056,0.005475,0.004936,0.004437,0.003978,0.003555,0.003168,0.002814,0.002492,0.002199,0.001934,0.001695,0.001481,0.001288,0.001116,0.000963,0.000828,0.000708,0.000603,0.000511,0.000431,0.000361,0.000301,0.000250,0.000206,0.000168,0.000137,0.000110,0.000088,0.000070,0.000055,0.000043,0.000033,0.000025,0.000019,0.000014,0.000010,0.000007,0.000005,0.000004,0.000002,0.000002,0.000001,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000};

static float betaDist4[100] = {0.003996,0.007596,0.010824,0.013703,0.016255,0.018501,0.020460,0.022153,0.023597,0.024809,0.025807,0.026607,0.027223,0.027671,0.027963,0.028114,0.028135,0.028038,0.027834,0.027535,0.027149,0.026687,0.026157,0.025567,0.024926,0.024240,0.023517,0.022763,0.021983,0.021184,0.020371,0.019548,0.018719,0.017890,0.017062,0.016241,0.015428,0.014627,0.013839,0.013068,0.012315,0.011582,0.010870,0.010181,0.009515,0.008874,0.008258,0.007668,0.007103,0.006565,0.006053,0.005567,0.005107,0.004673,0.004264,0.003880,0.003521,0.003185,0.002872,0.002581,0.002312,0.002064,0.001835,0.001626,0.001434,0.001260,0.001102,0.000959,0.000830,0.000715,0.000612,0.000521,0.000440,0.000369,0.000308,0.000254,0.000208,0.000169,0.000136,0.000108,0.000084,0.000065,0.000050,0.000037,0.000027,0.000019,0.000014,0.000009,0.000006,0.000004,0.000002,0.000001,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000};

Now I'm trying to actually generate those arrays, by plugging in the values (a = 1.0, b = 8.0/11.3333/18.0) into the Python scipy.stats.beta (4) module:

#!/usr/bin/env python3

from scipy.stats import beta
import sys

a = 1.0
bs = [8.0, 11.33333333, 18.0]

beta_distrib_1 = [[] for _ in range(3)]
beta_distrib_2 = [[] for _ in range(3)]

for i in range(100):
    for j, b in enumerate(bs):
        beta_distrib_1[j].append(beta.pdf(i, a, b))
        beta_distrib_2[j].append(beta.pdf(i, a, b))

print(beta_distrib_1)
print(beta_distrib_2)

However, the output is not even close to those hardcoded arrays. Could somebody describe how to go from a=1.0,b=8.0 to those actual arrays of values? Should I be using the pdf function? What's the parameter x? Say I want to do something similar, but with 20 values instead of 100.

Additionally, if I use beta(1.0, 8.0), beta(1.0, 11.333), beta(1.0, 18.0), the means are not 0.1, 0.15, and 0.20 in scipy.

Also, my ultimate goal is to use the Boost C++ beta distribution library (5) - but I assume that once I understand the math behind the idea, I'll be able to proceed with any library in any language