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 A216594 #19 Nov 02 2012 13:21:51 %S A216594 28,40,44,63,76,88,92,104,105,112,117,124,152,165,172,176,184,188,189, %T A216594 195,208,224,225,231,232,236,248,268,275,279,284,285,296,304,315,316, %U A216594 332,344,352,357,368,375,376,385,387,412,416,424,428,429,464,472,483 %N A216594 Numbers which are not nilpotent numbers, but every group of that order has nontrivial center. %C A216594 If p > 3 is a prime and p == 3 (mod 4), then 4p is in this sequence. Since there exist infinitely many primes of the form 4k + 3, this sequence is infinite. %H A216594 Mikko Korhonen, <a href="/A216594/b216594.txt">Table of n, a(n) for n = 1..200</a> %e A216594 Every group of order 28 has nontrivial center, but the dihedral group of order 28 is not nilpotent. %Y A216594 Subsequence of A056868. %K A216594 nonn %O A216594 1,1 %A A216594 _Mikko Korhonen_, Sep 09 2012