A121565 - OEIS

A121565

a(n) is the numerator of Sum_{i=1..n} i!/(i^2).

0, 1, 3, 13, 11, 127, 427, 13789, 79939, 550339, 4360579, 428990369, 4270982369, 608769618797, 7287249426797, 94552718917997, 1321723383637997, 336624987690165949, 5380569124281525949, 1736468713616949633031, 31234462813230541185031, 593101017091584665985031

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..21.

FORMULA

Numerator of Sum_{i=1..n} A000142(i)/A000290(i).

MATHEMATICA

Join[{0}, Accumulate[Table[k!/k^2, {k, 30}]]]//Numerator (* Harvey P. Dale, Feb 21 2024 *)

PROG

(PARI) a(n) = numerator(sum(i=1, n, i!/i^2)); \\ Michel Marcus, Mar 18 2018

CROSSREFS