%I #21 Dec 11 2024 23:41:35
%S 1,1,1,1,6,4,1,1,1,6,4,14,2,24,1,1,3,1,2,2,4,12,12,1,1,2,8,2,6,8,1,3,
%T 6,6,1,1,2,4,2,6,6,4,4,6,6,24,4,1,3,3,2,2,6,24,24,40,10,30,12,2,2,8,1,
%U 1,12,4,2,6,48,72,3,1,2,2,4,4,24,8,2,1,1,42,28,4,12,12,60,90,18,2,56,8
%N a(n) = gcd(sigma(n+1), sigma(n)), where sigma = A000203.
%H Harry J. Smith, <a href="/A060780/b060780.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = gcd(A000203(n+1), A000203(n)).
%p seq(igcd(numtheory:-sigma(n+1),numtheory:-sigma(n)),n=1..100); # _Robert Israel_, Jul 03 2017
%t Table[GCD[DivisorSigma[1, n + 1], DivisorSigma[1, n]] , {n, 1, 50}] (* _G. C. Greubel_, Jul 03 2017 *)
%o (PARI) a(n) = { gcd(sigma(n), sigma(n+1)) } \\ _Harry J. Smith_, Jul 11 2009
%Y Cf. A000203, A058075.
%K nonn
%O 1,5
%A _Labos Elemer_, Apr 26 2001
%E Name corrected by _Robert Israel_, Jul 03 2017