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A198801
Number of closed paths of length 19n whose steps are 19th roots of unity.
1
1, 121645100408832000, 997586474354936812896742294502400000000, 66507379539349211518364492838558005847493108039680000000000000, 11256716378122801825351385824819232115042452248916289339300576523719750000000000000000
OFFSET
0,2
COMMENTS
Equivalently, the number of paths of length 19n in Z^19 from {0}^19 to {n}^19. - Andrew Howroyd, Nov 01 2018
LINKS
Gilbert Labelle and Annie Lacasse, Closed paths whose steps are roots of unity, in FPSAC 2011, Reykjavik, Iceland DMTCS proc. AO, 2011, 599-610.
FORMULA
a(n) = (19*n)!/(n!)^19. - Andrew Howroyd, Nov 01 2018
PROG
(PARI) a(n) = (19*n)!/(n!)^19; \\ Andrew Howroyd, Nov 01 2018
CROSSREFS
Row n=19 of A187783, column k=19 of A089759.
Sequence in context: A095433 A099727 A011530 * A317259 A317914 A317255
KEYWORD
nonn
AUTHOR
Simon Plouffe, Oct 30 2011
EXTENSIONS
Sequence redefined and a(2)-a(4) from Andrew Howroyd, Nov 01 2018
STATUS
approved