Fermat pseudoprimes

func generate_fermat_psp(base, upto, n) {

    if (base == 1) {
        return(n.by { .is_composite }, upto.composite_count)
    }

    var psp = []

    for k in (1..Inf) {
        break if (k.pn_primorial > upto)
        psp << k.fermat_psp(base, 1, upto)...
    }

    return(psp.sort.first(n), psp.len)
}

var upto = 1e7

for base in (1..20) {
    var (psp, count) = generate_fermat_psp(base, upto, 20)
    printf("Base %2d - up to #{upto}: %7d  First 20: %s\n", base, count, psp)
}

Output:

Base  1 - up to 10000000: 9335420  First 20: [4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32]
Base  2 - up to 10000000:     750  First 20: [341, 561, 645, 1105, 1387, 1729, 1905, 2047, 2465, 2701, 2821, 3277, 4033, 4369, 4371, 4681, 5461, 6601, 7957, 8321]
Base  3 - up to 10000000:     760  First 20: [91, 121, 286, 671, 703, 949, 1105, 1541, 1729, 1891, 2465, 2665, 2701, 2821, 3281, 3367, 3751, 4961, 5551, 6601]
Base  4 - up to 10000000:    1347  First 20: [15, 85, 91, 341, 435, 451, 561, 645, 703, 1105, 1247, 1271, 1387, 1581, 1695, 1729, 1891, 1905, 2047, 2071]
Base  5 - up to 10000000:     745  First 20: [4, 124, 217, 561, 781, 1541, 1729, 1891, 2821, 4123, 5461, 5611, 5662, 5731, 6601, 7449, 7813, 8029, 8911, 9881]
Base  6 - up to 10000000:     895  First 20: [35, 185, 217, 301, 481, 1105, 1111, 1261, 1333, 1729, 2465, 2701, 2821, 3421, 3565, 3589, 3913, 4123, 4495, 5713]
Base  7 - up to 10000000:     659  First 20: [6, 25, 325, 561, 703, 817, 1105, 1825, 2101, 2353, 2465, 3277, 4525, 4825, 6697, 8321, 10225, 10585, 10621, 11041]
Base  8 - up to 10000000:    1993  First 20: [9, 21, 45, 63, 65, 105, 117, 133, 153, 231, 273, 341, 481, 511, 561, 585, 645, 651, 861, 949]
Base  9 - up to 10000000:    1418  First 20: [4, 8, 28, 52, 91, 121, 205, 286, 364, 511, 532, 616, 671, 697, 703, 946, 949, 1036, 1105, 1288]
Base 10 - up to 10000000:     766  First 20: [9, 33, 91, 99, 259, 451, 481, 561, 657, 703, 909, 1233, 1729, 2409, 2821, 2981, 3333, 3367, 4141, 4187]
Base 11 - up to 10000000:     695  First 20: [10, 15, 70, 133, 190, 259, 305, 481, 645, 703, 793, 1105, 1330, 1729, 2047, 2257, 2465, 2821, 4577, 4921]
Base 12 - up to 10000000:    1091  First 20: [65, 91, 133, 143, 145, 247, 377, 385, 703, 1045, 1099, 1105, 1649, 1729, 1885, 1891, 2041, 2233, 2465, 2701]
Base 13 - up to 10000000:     750  First 20: [4, 6, 12, 21, 85, 105, 231, 244, 276, 357, 427, 561, 1099, 1785, 1891, 2465, 2806, 3605, 5028, 5149]
Base 14 - up to 10000000:     817  First 20: [15, 39, 65, 195, 481, 561, 781, 793, 841, 985, 1105, 1111, 1541, 1891, 2257, 2465, 2561, 2665, 2743, 3277]
Base 15 - up to 10000000:     628  First 20: [14, 341, 742, 946, 1477, 1541, 1687, 1729, 1891, 1921, 2821, 3133, 3277, 4187, 6541, 6601, 7471, 8701, 8911, 9073]
Base 16 - up to 10000000:    1749  First 20: [15, 51, 85, 91, 255, 341, 435, 451, 561, 595, 645, 703, 1105, 1247, 1261, 1271, 1285, 1387, 1581, 1687]
Base 17 - up to 10000000:     763  First 20: [4, 8, 9, 16, 45, 91, 145, 261, 781, 1111, 1228, 1305, 1729, 1885, 2149, 2821, 3991, 4005, 4033, 4187]
Base 18 - up to 10000000:    1161  First 20: [25, 49, 65, 85, 133, 221, 323, 325, 343, 425, 451, 637, 931, 1105, 1225, 1369, 1387, 1649, 1729, 1921]
Base 19 - up to 10000000:     932  First 20: [6, 9, 15, 18, 45, 49, 153, 169, 343, 561, 637, 889, 905, 906, 1035, 1105, 1629, 1661, 1849, 1891]
Base 20 - up to 10000000:     850  First 20: [21, 57, 133, 231, 399, 561, 671, 861, 889, 1281, 1653, 1729, 1891, 2059, 2413, 2501, 2761, 2821, 2947, 3059]