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 A242331 #12 Sep 08 2022 08:46:08 %S A242331 1,6,16,18,20,24,26,32,34,36,40,44,46,48,56,60,66,68,78,80,88,98,100, %T A242331 102,104,108,116,118,120,128,136,148,152,164,170,174,176,182,188,190, %U A242331 192,196,200,204,212,220,226,232,234,238,246,250,252,258,260,262,266 %N A242331 Numbers k such that k^2 + 3 is a semiprime. %C A242331 The semiprimes of this form are: 4, 39, 259, 327, 403, 579, 679, 1027, 1159, 1299, 1603, 1939, 2119, 2307, 3139, 3603, 4359, 4627, ... %H A242331 Vincenzo Librandi, <a href="/A242331/b242331.txt">Table of n, a(n) for n = 1..1000</a> %t A242331 Select[Range[300], PrimeOmega[#^2 + 3] == 2 &] %o A242331 (Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [n: n in [0..300] | IsSemiprime(s) where s is n^2+3]; %Y A242331 Cf. A049422, A049423, A085722, A242330, A242332, A242333. %K A242331 nonn,easy %O A242331 1,2 %A A242331 _Vincenzo Librandi_, May 14 2014