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 A026845 #17 Jun 27 2022 21:18:48
%S A026845 1,8,81,1424,32152,1144937,53178768,3360267976,268737034880,
%T A026845 26735641360265,3222856389284352,463078022054303432,
%U A026845 78131995260953112576,15295767841794798044432,3438384401028669096232665,879589866427669147125523584,254053056142392070125392290952
%N A026845 Sum_{mu a partition of n} (f^mu/n!)^{-2} where f^mu is the number of standard Young tableaux of shape mu.
%C A026845 Arises from counting coverings of a genus g=2 Riemann surface - expansion of generating function A_g(q) = sum_{n>=0} a_{n,g} q^n where a_{n,g} = sum_{mu a partition of n} (f^mu/n!)^{2-2g}; note that A_0(q) = e^q and A_1(q) = prod_{i>=1} 1/(1-q^i).
%H A026845 Alois P. Heinz, <a href="/A026845/b026845.txt">Table of n, a(n) for n = 1..60</a>
%t A026845 (* version 4.0 *) Needs["DiscreteMath`Combinatorica`"]; Table[Tr[(n!/ (NumberOfTableaux /@ Partitions[n]))^2],{n,20}] (* _Wouter Meeussen_, Sep 30 2010 *)
%Y A026845 Cf. A047874. - _Wouter Meeussen_, Sep 30 2010
%K A026845 nonn
%O A026845 1,2
%A A026845 _Bruce E. Sagan_, Apr 06 2002
%E A026845 Terms 8 to 20 added by _Wouter Meeussen_, Sep 30 2010