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 A172015 #6 Nov 24 2016 06:05:15
%S A172015 23,25,47,49,53,55,83,85,89,91,113,115,131,133,167,169,173,175,233,
%T A172015 235,251,253,257,259,263,265,293,295,317,319,353,355,359,361,383,385,
%U A172015 389,391,401,403,443,445,449,451,467,469,479,481,491,493,503,505,509,511
%N A172015 Numbers of the form 6*k-+1 such that 6*k-1=prime and 6*k+1=nonprime.
%t A172015 Select[Table[{6k-1, 6k+1}, {k, 1, 100}], PrimeQ[ #[[1]] ] && !PrimeQ[ #[[2]] ]&] // Flatten (* _Jean-François Alcover_, Nov 24 2016 *)
%Y A172015 A171688 U A171697 U A172015 U A172016 = A007310.
%K A172015 nonn
%O A172015 1,1
%A A172015 _Juri-Stepan Gerasimov_, Jan 22 2010
%E A172015 Entries checked by _R. J. Mathar_, Apr 14 2010