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 A198801 #19 Feb 06 2024 08:12:50
%S A198801 1,121645100408832000,997586474354936812896742294502400000000,
%T A198801 66507379539349211518364492838558005847493108039680000000000000,
%U A198801 11256716378122801825351385824819232115042452248916289339300576523719750000000000000000
%N A198801 Number of closed paths of length 19n whose steps are 19th roots of unity.
%C A198801 Equivalently, the number of paths of length 19n in Z^19 from {0}^19 to {n}^19. - _Andrew Howroyd_, Nov 01 2018
%H A198801 Andrew Howroyd, <a href="/A198801/b198801.txt">Table of n, a(n) for n = 0..40</a>
%H A198801 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 A198801 a(n) = (19*n)!/(n!)^19. - _Andrew Howroyd_, Nov 01 2018
%o A198801 (PARI) a(n) = (19*n)!/(n!)^19; \\ _Andrew Howroyd_, Nov 01 2018
%Y A198801 Row n=19 of A187783, column k=19 of A089759.
%K A198801 nonn
%O A198801 0,2
%A A198801 _Simon Plouffe_, Oct 30 2011
%E A198801 Sequence redefined and a(2)-a(4) from _Andrew Howroyd_, Nov 01 2018