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 A037231 #13 Feb 16 2025 08:32:37
%S A037231 2,3,7,23,43,139,283,659,1319,5179,9227,23159,55399,148439,366683,
%T A037231 793439,1953839,4875119,9750239,27353747,71815607,192287243,430893643
%N A037231 Primes which set a new record for length of Pratt certificate.
%H A037231 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrattCertificate.html">Pratt Certificate</a>.
%t A037231 a[1] = 1; a[n_] := a[n] = 1 + Plus @@ (a@ PrimePi@ # & /@ First /@ FactorInteger[ Prime@ n - 1]); t = Table[ 0, {25}]; k = 2; While[k < 23420001, b = a[k]/2; If[b < 1001 && t[[b]] == 0, t[[b]] = Prime@ k; Print[{b, Prime@ k }]]; k++]; t
%Y A037231 Cf. A037202.
%K A037231 nonn,more
%O A037231 1,1
%A A037231 _David W. Wilson_