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 A367551 #11 Nov 22 2023 10:48:33
%S A367551 2,29,1008,84162,11881408,2566742098,781250000128,318651789038947,
%T A367551 167619551409708544,110462353708225871026,89116503268220597579776,
%U A367551 86380568889558343409300388,99045780329059370000000008192
%N A367551 a(n) = Sum_{d|n} (d^2+1)^n.
%F A367551 a(n) = Sum_{k=0..n} binomial(n,k) * sigma_{2*k}(n).
%o A367551 (PARI) a(n) = sumdiv(n, d, (d^2+1)^n);
%Y A367551 Cf. A163190, A308570, A367552.
%K A367551 nonn
%O A367551 1,1
%A A367551 _Seiichi Manyama_, Nov 22 2023