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- #!/usr/bin/ruby
- # a(n) is the least n-gonal number that is the product of n distinct primes, or 0 if there are none.
- # https://oeis.org/A359854
- # Known terms:
- # 6, 66, 0, 11310, 303810, 28962934, 557221665, 15529888374, 1219300152070
- func a(n) {
- return 0 if (n == 4)
- for k in (1..Inf) {
- if (k.polygonal(n).is_squarefree_almost_prime(n)) {
- return k.polygonal(n)
- }
- }
- }
- for n in (2..100) {
- say "a(#{n}) = #{a(n)}"
- }
- __END__
- a(2) = 6
- a(3) = 66
- a(4) = 0
- a(5) = 11310
- a(6) = 303810
- a(7) = 28962934
- a(8) = 557221665
- a(9) = 15529888374
- a(10) = 1219300152070
- a(11) = 23900058257790
- a(12) = 1231931106828345
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