experimental-projects/oeis-research/Amiram Eldar/Abundant Carmichael numbers/comb.pl

#!/usr/bin/perl

use 5.014;
use ntheory qw(forcomb carmichael_lambda divisors is_prime binomial);
use Math::Prime::Util::GMP qw(is_carmichael vecprod);

#~ 1.8173 record: 64075459460541239985
#~ 1.8274 record: 14370921672011352376545
#~ 1.8670 record: 100724996094964745183793345
#~ 1.8937 record: 5981802520294676451270038145
#~ 1.9103 record: 141934960805533535384100259905
#~ 1.9103 record: 2609668563371076823446624111609234945
#~ 1.9176 record: 871005264581548962932418919531990803260747265
#~ 1.9296 record: 74875990602425226938138664024259158432269224416705
#~ 1.9332 record: 1018329989576989704159754753835889677652405111555820545
#~ 1.9483 record: 165502573617193579886078524884554371013787876466850820614145
#~ 1.9498 record: 14701083488299057530174696885922722686956286485260401577115414785
#~ 1.9540 record: 321030150905393790929751720043602006651739765349595158023943724894346115208705

#my @p = (3, 5, 17, 23, 29, 83, 89, 353, 449);
#my @p = (3, 5, 17, 23, 29);
#my @p = (3, 5, 17, 23, 29);
#my @p = (3, 5, 17, 23, 29, 83, 89);

#my @p = (3, 5, 17, 23, 29, 83, 89, 113, 197, 353, 449, 617);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 353, 449);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 353, 449, 617);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113);
#my @p = (3, 5, 17, 23, 29, 83, 89, 113, 197, 353, 449, 617, 3137);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 353, 449, 617, 4019, 656657);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113);
#my @p = (3, 5, 17, 23, 29, 43, 53, 89, 113, 127);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 257, 353, 617);
#my @p = (3, 5, 17, 23, 29);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 353, 449, 617);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 257, 353, 449, 617);
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 1409, 3137, 10193, 16073, 23297, 88397, 896897, 1500929, 18386369);

my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 353, 617);     # seems promising
#my @p = (3, 5, 17, 23, 29, 53, 83, 89, 113, 197, 257, 353, 617);

my $P = vecprod(@p);
#my $C = "37839385943068863406967633413004957540054532539686888463944906014566240419460804270776358938980032660929917901837033235462145";
#my $C = "772459017179480479061611372132330246001039753130436193419524315193543873326133868681083905";
my $C = "321030150905393790929751720043602006651739765349595158023943724894346115208705";
#my $C = "463149379463251167706230703520995680069543921166639491398457345";
my $L = carmichael_lambda($C);

#$L = 4352299952*128;
#$L = vecprod(2, 2, 2, 2, 2, 2, 2, 2, 7, 7, 7, 11, 13, 41);

#$L *= 2;
#$L *= 7;
#$L = 294181888;

say "lambda = $L";
my @divisors = divisors($L);

@divisors = grep { $_ > 1 and is_prime($_+1) } @divisors;
@divisors = map{ $_ + 1 } @divisors;
@divisors = grep { "@p" !~ /\b$_\b/ } @divisors;

#@divisors = (53, 257, 1409, 2003, 2297, 2549, 3137, 3329, 4019, 8009, 9857, 10193, 13313, 16073, 23297, 50177, 50513, 68993, 88397, 93809, 202049, 275969, 375233, 656657, 896897, 1500929, 3232769, 18386369, 22629377);

say "Primes = {", join(', ', @divisors), '}';

my $len = scalar(@divisors);

printf("binomial(%s, %s) = %s\n", $len, $len>>1, binomial($len, $len>>1));

foreach my $k(1..scalar(@divisors)) {
    say "Testing: $k";
    forcomb {
        if (is_carmichael(vecprod(@divisors[@_],$P))) {
            say vecprod(@divisors[@_], $P);
        }
    } $len, $k;
}

__END__
166320 -> 3649
15120 -> 2972
110880 -> 2925
55440 -> 2828
277200 -> 2775
25200 -> 2685
196560 -> 2586
332640 -> 2572
75600 -> 2483
65520 -> 2432
131040 -> 2274
720720 -> 2217
327600 -> 2185
100800 -> 2114
45360 -> 1964
221760 -> 1957
30240 -> 1940
831600 -> 1937
257040 -> 1917
60480 -> 1899

7201568 -> 1
4352299952 -> 1
5789168 -> 1
2618528 -> 1
2700544 -> 1
285824 -> 1
1350272 -> 1

2520 -> 226
3960 -> 141
3360 -> 128
3600 -> 127
2160 -> 119
4680 -> 114
6120 -> 106
6336 -> 95
5940 -> 86
4032 -> 82
6048 -> 67
1680 -> 65
9000 -> 63
9072 -> 61
4200 -> 60
3024 -> 53
4320 -> 52
1260 -> 52
4800 -> 52
9720 -> 48

1093200 -> 4
1012480 -> 3
1568400 -> 3
19153848 -> 2
1086840 -> 2
6984864 -> 2
2495532 -> 2
1320840 -> 2
1649640 -> 2
1461564 -> 2
1754970 -> 2
1840230 -> 2
5145300 -> 2
4156860 -> 2
2716452 -> 2
3715860 -> 2
1402092 -> 2
6531960 -> 2
1236300 -> 2
1626576 -> 2