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 A348350 #15 Oct 15 2021 08:38:33
%S A348350 1,5,28,4101,3126,362797088,823544,4398046515205,282429536509,
%T A348350 100000000000003130,285311670612,137370551967459378662949775392,
%U A348350 302875106592254,229585692886981495483044092,1122274146401882171630862528
%N A348350 a(n) = Sum_{d|n} d^(sigma(d) - 1).
%F A348350 G.f.: Sum_{k>=1} k^(sigma(k) - 1) * x^k/(1 - x^k).
%F A348350 If p is prime, a(p) = 1 + p^p.
%t A348350 a[n_] := DivisorSum[n, #^(DivisorSigma[1, #] - 1) &]; Array[a, 14] (* _Amiram Eldar_, Oct 14 2021 *)
%o A348350 (PARI) a(n) = sumdiv(n, d, d^(sigma(d)-1));
%o A348350 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, k^(sigma(k)-1)*x^k/(1-x^k)))
%Y A348350 Cf. A000203, A174472, A347991, A348223, A348349.
%K A348350 nonn
%O A348350 1,2
%A A348350 _Seiichi Manyama_, Oct 14 2021