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 A372491 #15 May 06 2024 12:30:52
%S A372491 2,3,4,5,11,17,32,53,103,107,109,113,137,197,233,811,7993,9281,14387,
%T A372491 26573,51361
%N A372491 Indices k such that A002533(k) is prime.
%C A372491 All terms are either primes or powers of 2.
%F A372491 A111011(n) = A002533(a(n)).
%e A372491 a(3) = 4 is a term because A002533(4) = 73 is prime.
%p A372491 B[0]:= 1: B[1]:= 1: R:= NULL: count:= 0:
%p A372491 for n from 2 while count < 18 do
%p A372491 B[n]:= 2*B[n-1]+5*B[n-2];
%p A372491 if (isprime(n) or n = 2^padic:-ordp(n,2)) and isprime(A[n]) then
%p A372491 R:= R,n; count:= count+1
%p A372491 fi
%p A372491 od:
%p A372491 R;
%t A372491 Flatten[Position[LinearRecurrence[{2, 5}, {1, 1}, 1000] ,_Integer?PrimeQ]-1] (* _James C. McMahon_, May 06 2024 *)
%Y A372491 Cf. A002533, A111011.
%K A372491 nonn,more
%O A372491 1,1
%A A372491 _Robert Israel_, May 03 2024
%E A372491 a(21) from _Michael S. Branicky_, May 04 2024