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 A350306 #11 Dec 24 2021 11:04:24
%S A350306 1,1,3,57,2855,459597,240485241,395649695145,2023017357650345,
%T A350306 31899582278283495743,1542718311570632349138107,
%U A350306 227912729019868361872929934159,102547791095886594007005283976727239,140202209701199998336689204011032887220183
%N A350306 a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^k.
%t A350306 a[n_] := Coefficient[Series[Product[(x^k + 1 + 1/x^k)^k, {k, 1, n}], {x, 0, 0}], x, 0]; Array[a, 14, 0] (* _Amiram Eldar_, Dec 24 2021 *)
%o A350306 (PARI) a(n) = polcoef(prod(k=1, n, (x^k+1+1/x^k)^k), 0);
%Y A350306 Cf. A350283, A350305, A350308.
%K A350306 nonn
%O A350306 0,3
%A A350306 _Seiichi Manyama_, Dec 23 2021