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 A138030 #10 Jul 09 2025 23:32:36 %S A138030 85864769,198479579,305192579,2400025739,7606886429,7755909149, %T A138030 10378311899,16744125509,17029114499,17117793089,17574340739, %U A138030 26089808579,28889527679,43390196519,45424068359,52179617159,54293956289,56838102179,65639153579,66655116659 %N A138030 Numbers that remain prime through 8 iterations of function f(x) = 2x + 1. %F A138030 a(n) == 89 or 329 (mod 330). - _John Cerkan_, Nov 30 2016 %t A138030 Select[Prime[Range[10^8]],PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1]&&PrimeQ[a6=2*a5+1]&&PrimeQ[a7=2*a6+1]&&PrimeQ[a8=2*a7+1] &] %K A138030 nonn %O A138030 1,1 %A A138030 _Vladimir Joseph Stephan Orlovsky_, May 01 2008