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 A198807 #21 Feb 06 2024 08:10:31
%S A198807 1,6227020800,49229914688306352000000,
%T A198807 1561776277448122046153927884800000000,
%U A198807 92024242230271040357108320801872044844750000000000,7708574168669332219803079339976372645861971547841327593737420800
%N A198807 Number of closed paths of length 13n whose steps are 13th roots of unity.
%C A198807 Equivalently, the number of paths of length 13n in Z^13 from {0}^13 to {n}^13. - _Andrew Howroyd_, Nov 01 2018
%H A198807 Gilbert Labelle and Annie Lacasse, <a href="https://doi.org/10.46298/dmtcs.2937">Closed paths whose steps are roots of unity</a>, in FPSAC 2011, Reykjavik, Iceland DMTCS proc. AO, 2011, 599-610.
%F A198807 a(n) = (13*n)!/(n!)^13. - _Andrew Howroyd_, Nov 01 2018
%o A198807 (PARI) a(n) = (13*n)!/(n!)^13; \\ _Andrew Howroyd_, Nov 01 2018
%Y A198807 Row n=13 of A187783, column k=13 of A089759.
%K A198807 nonn
%O A198807 0,2
%A A198807 _Simon Plouffe_, Oct 30 2011
%E A198807 Sequence redefined and a(2)-a(5) from _Andrew Howroyd_, Nov 01 2018