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 A057950 #16 Dec 01 2018 23:24:40
%S A057950 441,693,1089,1197,1449,1617,1881,1953,2277,2541,2709,2793,2961,3069,
%T A057950 3249,3381,3717,3933,4221,4257,4389,4473,4557,4653,4761,4977,5229,
%U A057950 5301,5313,5841,5929,6321,6417,6489,6633,6741,6897,6909,7029,7161,7353,7581
%N A057950 Numbers primitive with respect to having more than one factorization into S-primes. See related sequences for definition.
%C A057950 A subset of A057949, removing terms that are a multiple of a smaller term.
%C A057950 Cubefree numbers with exactly 4 prime factors, all congruent to 3 mod 4. - _Charlie Neder_, Nov 26 2018
%H A057950 Eric M. Schmidt, <a href="/A057950/b057950.txt">Table of n, a(n) for n = 1..10000</a>
%e A057950 441 is in S = {1, 5, 9, ... 4i+1, ...}, 441 = 9*49 = 21^2, 9, 21 and 49 as S-primes (A057948). 441 is primitive because it is not divisible by any smaller numbers with more than 1 factorization into S-primes. Multiples of 441 within S are not primitive.
%Y A057950 Cf. A054520, A057948, A057949.
%Y A057950 Cf. A004709 (cubefree numbers).
%K A057950 nonn
%O A057950 1,1
%A A057950 _Jud McCranie_, Oct 14 2000
%E A057950 Definition edited and offset corrected by _Eric M. Schmidt_, Dec 11 2016