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 A023586 #14 Jun 09 2019 04:01:21 %S A023586 1,1,2,1,1,2,1,1,2,1,1,1,4,1,1,1,2,2,1,1,1,1,1,1,1,1,1,1,1,2,1,2,1,1, %T A023586 3,1,1,2,2,1,1,2,1,1,1,1,1,1,1,1,1,2,1,1,3,1,1,1,1,1,1,2,1,3,4,1,1,1, %U A023586 2,1,1,1,1,1,1,2,1,1,2,1,3,2,1,1,1,1,1,1,1,2,1,1,1,2,1,1,2,1,1 %N A023586 Exponent of least prime factor in prime factorization of 2*prime(n)-1. %C A023586 First differs from A023584 at n = 56. - _Sean A. Irvine_, Jun 07 2019 %H A023586 Sean A. Irvine, <a href="/A023586/b023586.txt">Table of n, a(n) for n = 1..1000</a> %o A023586 (PARI) a(n) = factor(2*prime(n)-1)[1, 2]; \\ _Michel Marcus_, Jun 08 2019 %Y A023586 Cf. A023854. %K A023586 nonn %O A023586 1,3 %A A023586 _Clark Kimberling_ %E A023586 Title corrected by _Sean A. Irvine_, Jun 07 2019