cp's OEIS Frontend

A348977 a(n) = gcd(sigma(n), A332993(n)).

%I A348977 #9 Feb 15 2023 13:56:30
%S A348977 1,3,4,7,6,2,8,15,13,2,12,2,14,2,3,31,18,1,20,6,1,2,24,2,31,2,40,2,30,
%T A348977 3,32,63,3,2,1,1,38,2,1,2,42,1,44,6,6,2,48,2,57,3,3,2,54,2,1,2,1,2,60,
%U A348977 3,62,2,4,127,1,3,68,6,3,1,72,1,74,2,2,2,1,1,80,6,121,2,84,1,1,2,3,2,90,78,7,6,1,2,5
%N A348977 a(n) = gcd(sigma(n), A332993(n)).
%H A348977 Antti Karttunen, <a href="/A348977/b348977.txt">Table of n, a(n) for n = 1..16384</a>
%H A348977 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A348977 a(n) = gcd(A000203(n), A332993(n)).
%F A348977 a(n) = gcd(A000203(n), A333783(n)) = gcd(A332993(n), A333783(n)).
%F A348977 a(n) = A332993(n) / A348978(n) = A000203(n) / A348979(n).
%t A348977 f[n_] := n/FactorInteger[n][[1, 1]]; g[1] = 1; g[n_] := g[n] = n + g[f[n]]; a[n_] := GCD[g[n], DivisorSigma[1, n]]; Array[a, 100] (* _Amiram Eldar_, Nov 06 2021 *)
%o A348977 (PARI)
%o A348977 A332993(n) = if(1==n,n,n + A332993(n/vecmin(factor(n)[,1])));
%o A348977 A348977(n) = gcd(sigma(n), A332993(n));
%Y A348977 Cf. A000203, A332993, A333783, A348978, A348979.
%Y A348977 Cf. also A348987.
%K A348977 nonn
%O A348977 1,2
%A A348977 _Antti Karttunen_, Nov 06 2021