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 A139042 #9 Dec 16 2018 06:40:39 %S A139042 15,39,55,87,95,111,143,159,183,295,303,319,335,407,415,447,519,535, %T A139042 543,551,583,591,655,695,767,807,815,879,895,951,1007,1047,1055,1079, %U A139042 1119,1135,1167,1263,1383,1391,1527,1623,1639,1671,1703,1711,1735,1839,1895,1903,1919,1943 %N A139042 Composite numbers c for which A064287((c-1)/2)=1. %C A139042 Is there an n for which A006694((a(n)-1)/2) is not equal to 4? %Y A139042 Cf. A064287, A006694, A001122. %K A139042 nonn %O A139042 1,1 %A A139042 _Vladimir Shevelev_, Jun 01 2008 %E A139042 More terms (using A064287 b-file) from _Michel Marcus_, Dec 16 2018