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 A294614 #24 Mar 28 2024 09:03:02
%S A294614 0,0,1,0,0,0,0,2,0,2,0,2,3,0,0,0,3,4,0,0,0,0,8,4,3,0,3,6,0,0,5,0,7,4,
%T A294614 0,0,0,18,0,0,0,0,9,4,12,4,0,14,0,0,5,8,11,0,0,6,0,12,9,0,5,0,13,6,5,
%U A294614 10,7,14,0,0,5,0,31,0,5,0,7,30,0,12,0,0,17,6,0,0,13,18,9,8
%N A294614 Sum of the divisors of 12*n - 1, divided by 12, minus n.
%C A294614 a(n) = 0 iff n is in A138620.
%C A294614 First occurrence of k > -1: 1, 3, 8, 13, 18, 31, 28, 33, 23, 43, 66, 53, 45, 63, 48, 101, 166, etc.
%F A294614 a(n) = sigma(12*n-1)/12 - n = A000203(A017653(n-1))/12 - n.
%F A294614 Sum_{k=1..n} a(k) = c * n^2 + O(n*log(n)), where c = Pi^2/18 - 1/2 = 0.048311... . - _Amiram Eldar_, Mar 28 2024
%e A294614 a(13) = 3 since d(12*13-1)/12 - 13 = 192/12 - 13 = 16 - 13 = 3.
%t A294614 a[n_] := DivisorSigma[1, 12 n - 1]/12 - n; Array[a, 90]
%o A294614 (PARI) a(n) = sigma(12*n-1)/12 - n;
%Y A294614 Inspired by A291900.
%Y A294614 Cf. A000203, A017653, A068231, A086463, A138620.
%K A294614 nonn,easy
%O A294614 1,8
%A A294614 _Omar E. Pol_ and _Robert G. Wilson v_, Nov 04 2017