cp's OEIS Frontend

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.

A353785 a(n) = A353783(n) / A080398(n).

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%I A353785 #7 May 08 2022 19:50:45
%S A353785 1,1,2,1,1,2,4,1,1,1,2,2,1,4,2,1,3,1,2,1,4,2,4,2,1,1,4,4,1,2,16,3,2,3,
%T A353785 4,1,1,2,2,1,1,4,2,2,1,4,8,2,1,1,6,1,9,4,2,4,2,1,2,2,1,16,4,1,1,2,2,3,
%U A353785 4,4,12,1,1,1,2,2,4,2,8,1,11,1,2,4,3,2,2,2,3,1,4,4,16,8,2,6,7,1,2,1,1,6,4,1,4
%N A353785 a(n) = A353783(n) / A080398(n).
%H A353785 Michael De Vlieger, <a href="/A353785/b353785.txt">Table of n, a(n) for n = 1..10000</a>
%H A353785 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A353785 a(n) = A353783(n) / A080398(n).
%t A353785 Array[Apply[LCM, DivisorSigma[1, Power @@@ FactorInteger[#]]]/Apply[Times, FactorInteger[DivisorSigma[1, #]][[All, 1]]] &, 105] (* _Michael De Vlieger_, May 08 2022 *)
%o A353785 (PARI)
%o A353785 A080398(n) = factorback(factor(sigma(n))[, 1]);
%o A353785 A353783(n) = { my(f=factor(n)~); lcm(vector(#f, i, sigma(f[1, i]^f[2, i]))); };
%o A353785 A353785(n) = (A353783(n) / A080398(n));
%Y A353785 Cf. A000203, A080398, A353783.
%K A353785 nonn
%O A353785 1,3
%A A353785 _Antti Karttunen_, May 08 2022