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 A267504 #16 Feb 16 2021 02:09:28
%S A267504 2,3,7,23,43,47,67,139,283,463,659,947,967,1319,1699,1979,3083,4423,
%T A267504 5683,5839,6299,9227,10627,11887,13259,18679,19183,19447,19867,21407,
%U A267504 26539,30559,35863,37379,39199,41539,44087,44483,45403,55399,63823,71347,71359,74759,91127,91463,115099,130687,132527
%N A267504 Primes p such that p-1 is squarefree and all prime divisors of p-1 other than 11 are also in the sequence.
%C A267504 Is this sequence infinite?
%t A267504 fa = FactorInteger; is[2, p_] = True; is[2, p_];
%t A267504 is[n_, p_] := PrimeQ[n] && MoebiusMu[n - 1] ≠ 0 && Union@Table[is[fa[n - 1][[i, 1]], p] || fa[n - 1][[ i, 1]] == p , {i, Length[fa[n - 1]]}] == {True}; Select[Prime[Range[10000]], is[#, 11] &]
%Y A267504 Cf. A267503, A267505, A267506, A267507, A005117, A227455, A227007, A227006.
%K A267504 nonn
%O A267504 1,1
%A A267504 _José María Grau Ribas_, Jan 16 2016