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 A387156 #14 Aug 20 2025 08:06:59
%S A387156 1,1,2,1,1,2,4,1,1,3,2,2,1,4,4,1,3,1,2,1,16,6,4,2,1,1,4,4,1,12,16,3,8,
%T A387156 9,8,1,1,2,4,3,1,16,2,2,1,12,8,2,1,1,12,7,9,4,12,4,8,3,2,4,1,16,4,1,2,
%U A387156 24,2,3,16,24,12,1,1,1,2,2,16,4,8,1,11,3,2,16,18,2,4,6,3,3,8,4,64,24,4,6,7,3,2
%N A387156 a(n) = A003557(sigma(n)), where A003557(n) is multiplicative with a(p^e) = p^(e-1), and sigma is the sum of divisors function.
%H A387156 Antti Karttunen, <a href="/A387156/b387156.txt">Table of n, a(n) for n = 1..10000</a>
%F A387156 a(n) = A000203(n) / A080398(n).
%F A387156 a(n) = A062401(n) / A387157(n).
%t A387156 A387156[n_] := # / Times @@ FactorInteger[#][[All, 1]] & [DivisorSigma[1, n]];
%t A387156 Array[A387156, 100] (* _Paolo Xausa_, Aug 20 2025 *)
%o A387156 (PARI) A387156(n) = { my(s=sigma(n)); s/factorback(factor(s)[,1]); };
%Y A387156 Cf. A000203, A003557, A062401, A080398, A387157.
%Y A387156 Cf. also A386424, A386425.
%K A387156 nonn
%O A387156 1,3
%A A387156 _Antti Karttunen_, Aug 19 2025