cp's OEIS Frontend

A070010 GCD of consecutive values of sum-of-proper divisors.

%I A070010 #10 Oct 05 2017 15:57:25
%S A070010 1,1,1,1,1,1,1,1,4,1,1,1,1,1,3,1,1,1,1,11,1,1,1,6,2,1,1,1,1,1,1,1,5,1,
%T A070010 1,1,1,1,1,1,1,1,1,1,1,1,1,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%U A070010 1,1,1,1,1,1,1,1,1,1,1,2,4,1,1,1,23,1,1,1,1,3,1,1,5,25,1,1,1,1,3,1,1,1,1
%N A070010 GCD of consecutive values of sum-of-proper divisors.
%H A070010 Antti Karttunen, <a href="/A070010/b070010.txt">Table of n, a(n) for n = 1..10000</a>
%F A070010 a(n) = gcd(A001065(n+1), A001065(n)).
%t A070010 GCD[DivisorSigma[1, n+1]-(n+1), DivisorSigma[1, n]-n]
%o A070010 (PARI)
%o A070010 A001065(n) = (sigma(n) - n);
%o A070010 A070010(n) = gcd(A001065(n),A001065(1+n)); \\ _Antti Karttunen_, Oct 05 2017
%Y A070010 Cf. A000203, A001065; GCD of various consecutive function values: A048586, A057467, A058515, A060778, A060780, A069896.
%K A070010 nonn
%O A070010 1,9
%A A070010 _Labos Elemer_, Apr 11 2002