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 A253052 #4 Jan 01 2015 12:16:44 %S A253052 9,21,33,93,111,129,177,213,237,267,309,321,381,411,519,579,597,633, %T A253052 687,699,723,753,789,831,879,921,951,1047,1149,1257,1299,1317,1347, %U A253052 1401,1461,1641,1713,1731,1779,1797,1821,1983,2031,2049,2103,2181,2427,2469 %N A253052 If, for some m, A098550(m-2) is a prime p and A098550(m) = 3p, add 3p to the sequence. %C A253052 A subsequence of A251544 (and of course of A098550). %Y A253052 Cf. A098550, A251544, A253053, A253054. %K A253052 nonn %O A253052 1,1 %A A253052 _N. J. A. Sloane_, Jan 01 2015