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 A139787 #9 Nov 19 2019 03:35:55 %S A139787 9,15,21,25,33,49,51,69,87,93,111,115,129,133,141,159,169,201,205,219, %T A139787 235,237,259,267,289,303,319,321,327,339,361,391,393,415,427,451,489, %U A139787 511,517,519,529,535,537,553,559,579,583,591,655,679,685,699,717 %N A139787 Semiprime lucky numbers. %C A139787 Subset of A031879 Composite lucky numbers. %H A139787 Amiram Eldar, <a href="/A139787/b139787.txt">Table of n, a(n) for n = 1..10000</a> %F A139787 A000959 INTERSECTION A001358. %Y A139787 Cf. A000959, A001358, A031879. %K A139787 easy,nonn %O A139787 1,1 %A A139787 _Jonathan Vos Post_, May 20 2008 %E A139787 Term 135 deleted by _Giovanni Resta_, Jun 20 2016