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 A338810 #12 Nov 10 2020 09:33:35
%S A338810 0,1,6,28,170,988,7896,60492,555264,5819904,61776000,725950080,
%T A338810 9894493440,137963243520,1875645434880,33258387456000,528975488563200,
%U A338810 9760969019289600,175565885864140800,3608256006957772800,72367669059194880000,1745463407406243840000
%N A338810 a(n) = (n!/2) * Sum_{k=1..n-1} d(k)*d(n-k)/(k*(n-k)), where d(n) is the number of divisors of n.
%F A338810 a(n) = (n-1)! * Sum_{k=1..n-1} d(k)*d(n-k)/k.
%t A338810 a[n_] := (n - 1)! * Sum[DivisorSigma[0, k] * DivisorSigma[0, n - k]/k, {k, 1, n - 1} ]; Array[a, 22] (* _Amiram Eldar_, Nov 10 2020 *)
%o A338810 (PARI) {a(n)= n!*sum(k=1, n-1, numdiv(k)*numdiv(n-k)/(k*(n-k)))/2}
%o A338810 (PARI) {a(n)= (n-1)!*sum(k=1, n-1, numdiv(k)*numdiv(n-k)/k)}
%o A338810 (PARI) {a(n) = my(u='u); n!*polcoef(polcoef(prod(k=1, n, (1-x^k+x*O(x^n))^(-u/k)), n), 2)}
%Y A338810 Column 2 of A338805.
%Y A338810 Cf. A000005, A055507, A059356.
%K A338810 nonn
%O A338810 1,3
%A A338810 _Seiichi Manyama_, Nov 10 2020