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 A156155 #8 Feb 22 2020 03:43:10 %S A156155 2,6,21,51892,1686970 %N A156155 Numbers k such that prime(prime(k)) = 2 (mod prime(k)), where prime(k) = A000040(k) is the k-th prime. %F A156155 a(n) = A000720(A156154(n)). %o A156155 (PARI) p=c=0; until(0, until( isprime(c++), p=nextprime(p+1)); (p-2)%c & next; print1( primepi(c)",")) %Y A156155 Cf. A023144, A156154. %K A156155 nonn,more %O A156155 1,1 %A A156155 _M. F. Hasler_, Feb 04 2009 %E A156155 a(5) from _Jinyuan Wang_, Feb 22 2020