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A349270
a(n) = Sum_{k=0..n} (n - k)! * k! / floor(k / 2)!^2, row sums of A349269.
2
1, 2, 5, 16, 46, 204, 986, 6400, 48094, 420140, 4112822, 44575584, 528787260, 6811260792, 94637153172, 1410542965248, 22446384533142, 379801729831500, 6808478318116238, 128895044005636960, 2569653423591937156, 53808349548318974312, 1180737041228428129580
OFFSET
0,2
LINKS
MATHEMATICA
Table[Sum[(n-k)! k! / Floor[k/2]!^2, {k, 0, n}], {n, 0, 22}] (* Stefano Spezia, Nov 13 2021 *)
PROG
(PARI) a(n) = sum(k=0, n, (n - k)!*k!/(k\2)!^2); \\ Michel Marcus, Nov 13 2021
CROSSREFS
Cf. A349269.
Sequence in context: A306504 A148376 A148377 * A163865 A148378 A148379
KEYWORD
nonn
AUTHOR
Peter Luschny, Nov 13 2021
STATUS
approved