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 A006422 M3684 #17 May 15 2023 17:26:54
%S A006422 4,47,240,831,2282,5362,11256,21690,39072,66649,108680,170625,259350,
%T A006422 383348,552976,780708,1081404,1472595,1974784,2611763,3410946,4403718,
%U A006422 5625800,7117630,8924760,11098269,13695192,16778965,20419886,24695592,29691552,35501576
%N A006422 Number of rooted toroidal maps with 2 faces and n vertices and without separating cycles or isthmuses.
%D A006422 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006422 Andrew Howroyd, <a href="/A006422/b006422.txt">Table of n, a(n) for n = 1..1000</a>
%H A006422 T. R. S. Walsh and A. B. Lehman, <a href="http://dx.doi.org/10.1016/0095-8956(75)90050-7">Counting rooted maps by genus. III: Nonseparable maps</a>, J. Combinatorial Theory Ser. B 18 (1975), 222-259.
%H A006422 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).
%F A006422 From _Colin Barker_, Apr 09 2013: (Start)
%F A006422 a(n) = n*(n + 1)*(n + 2)*(8*n^3 + 87*n^2 + 148*n - 3)/360.
%F A006422 G.f.: x*(2*x^3+5*x^2-19*x-4) / (x-1)^7. (End)
%t A006422 LinearRecurrence[{7,-21,35,-35,21,-7,1},{4,47,240,831,2282,5362,11256},40] (* _Harvey P. Dale_, May 15 2023 *)
%o A006422 (PARI) a(n) = {n*(n + 1)*(n + 2)*(8*n^3 + 87*n^2 + 148*n - 3)/360}
%Y A006422 Column 2 of A343090.
%K A006422 nonn
%O A006422 1,1
%A A006422 _N. J. A. Sloane_
%E A006422 Name clarified and terms a(11) and beyond from _Andrew Howroyd_, Apr 04 2021