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 A357912 #22 Aug 09 2023 00:52:58
%S A357912 1,1,1,1,1,1,1,1,1,1,1,13,1,1,1,1,1,1,1,1,1,1,24,13,1,1,1,1,1,1,1,1,1,
%T A357912 35,1,13,1,1,1,1,1,1,1,1,46,24,1,13,1,1,1,1,1,1,1,57,1,1,1,13,1,1,1,1,
%U A357912 1,1,68,35,24,1,1,13,1,1,1,1,1,79,1,1,1,1,1,13,1
%N A357912 a(n) = Sum_{d|n, d==1 (mod 11)} d.
%H A357912 Seiichi Manyama, <a href="/A357912/b357912.txt">Table of n, a(n) for n = 1..10000</a>
%F A357912 G.f.: Sum_{k>=0} (11*k+1) * x^(11*k+1)/(1 - x^(11*k+1)).
%t A357912 a[n_] := DivisorSum[n, # &, Mod[#, 11] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Aug 09 2023 *)
%o A357912 (PARI) a(n) = sumdiv(n, d, (Mod(d, 11)==1)*d);
%o A357912 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=0, N, (11*k+1)*x^(11*k+1)/(1-x^(11*k+1))))
%Y A357912 Cf. Sum_{d|n, d==1 (mod k)} d: A000593 (k=2), A078181 (k=3), A050449 (k=4), A284097 (k=5), A284098 (k=6), A284099 (k=7), A284100 (k=8), this sequence (k=11).
%Y A357912 Cf. A357911.
%K A357912 nonn
%O A357912 1,12
%A A357912 _Seiichi Manyama_, Jan 17 2023