This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A343826 #24 May 26 2021 02:53:15 %S A343826 25,45,65,81,85,105,117,145,153,165,169,185,189,205,221,245,261,265, %T A343826 273,285,289,297,305,333,345,357,365,369,377,385,429,445,465,477,481, %U A343826 485,493,505,513,533,545,549,561,565,605,609,621,629,637,645,657,665,685 %N A343826 Numbers which are the product of two S-primes (A057948) in exactly one way. %C A343826 There exist numbers which are the product of two S-primes in exactly 1, 2, and 3 ways; however, it is unknown if any numbers exist which are the product of two S-primes in exactly 4 ways. %H A343826 Zachary DeStefano, <a href="/A343826/b343826.txt">Table of n, a(n) for n = 1..3786</a> %F A343826 a(n) == 1 (mod 4). - _Hugo Pfoertner_, May 01 2021 %e A343826 153 = 9*17 which are both S-primes, and admits no other S-prime factorizations. %o A343826 (PARI) \\ uses is(n) from A057948 %o A343826 isok(n) = sumdiv(n, d, (d<=n/d) && is(d) && is(n/d)) == 1; \\ _Michel Marcus_, May 01 2021 %Y A343826 Cf. A054520, A057948, A057949, A057950. %Y A343826 Exactly two ways: A343827. Exactly three ways: A343828. %K A343826 nonn %O A343826 1,1 %A A343826 _Zachary DeStefano_, Apr 30 2021