A068338 a(n) = n!^2 * Sum_{k=1..n} mu(k)/k^2, where mu(k) is the Moebius function.

1, 3, 23, 368, 8624, 324864, 15399936, 985595904, 79833268224, 8115008716800, 968747865292800, 139499692602163200, 23346005516963020800, 4614592869368384716800, 1045883450064438558720000, 267746163216496271032320000, 76940878032870027275796480000

Offset: 1

Author

Leroy Quet, Feb 27 2002

Keywords

• nonn

Links

• John Tyler Rascoe, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A008683, A068101, A068107, A068340.

Programs

PARI

A068338(n) = {n!^2 * sum(k=1,n,moebius(k)/k^2)} \\ John Tyler Rascoe, May 14 2025

Extensions

a(16) onwards from John Tyler Rascoe, May 14 2025