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 A066174 #11 Apr 07 2025 15:21:15
%S A066174 2879,2029439,4068479,12968639,25945919,34214399,35925119,37715519,
%T A066174 42684479,51158399,57794879,62663999,69255359,71850239,74543039,
%U A066174 83394239,91166399,103721279,106879679,121094399,126785279,130844159
%N A066174 First member of a prime sextet: p, (p-1)/2, (p-3)/4, (p-7)/8, (p-15)/16, (p-31)/32.
%t A066174 f[n_]:=(n-1)/2;lst={};Do[p=Prime[n];If[PrimeQ[a=f[p]],If[PrimeQ[b=f[a]],If[PrimeQ[c=f[b]],If[PrimeQ[d=f[c]],If[PrimeQ[e=f[d]],AppendTo[lst,p]]]]]],{n,11!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Mar 10 2010 *)
%t A066174 Select[Prime[Range[7424000]],AllTrue[{(#-1)/2,(#-3)/4,(#-7)/8,(#-15)/16,(#-31)/32},PrimeQ]&] (* _Harvey P. Dale_, Apr 07 2025 *)
%K A066174 nonn
%O A066174 1,1
%A A066174 _Vladeta Jovovic_, Dec 15 2001
%E A066174 More terms from _Don Reble_, Dec 17 2001