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 A060780 #21 Dec 11 2024 23:41:35
%S A060780 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 A060780 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 A060780 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 A060780 a(n) = gcd(sigma(n+1), sigma(n)), where sigma = A000203.
%H A060780 Harry J. Smith, <a href="/A060780/b060780.txt">Table of n, a(n) for n = 1..1000</a>
%F A060780 a(n) = gcd(A000203(n+1), A000203(n)).
%p A060780 seq(igcd(numtheory:-sigma(n+1),numtheory:-sigma(n)),n=1..100); # _Robert Israel_, Jul 03 2017
%t A060780 Table[GCD[DivisorSigma[1, n + 1], DivisorSigma[1, n]] , {n, 1, 50}] (* _G. C. Greubel_, Jul 03 2017 *)
%o A060780 (PARI) a(n) = { gcd(sigma(n), sigma(n+1)) } \\ _Harry J. Smith_, Jul 11 2009
%Y A060780 Cf. A000203, A058075.
%K A060780 nonn
%O A060780 1,5
%A A060780 _Labos Elemer_, Apr 26 2001
%E A060780 Name corrected by _Robert Israel_, Jul 03 2017