A099739 - OEIS

%I #15 May 19 2021 07:28:39

%S 1,-1,-7,-7,-127,593,-4447,-4447,-4447,3624353,-36292447,-36292447,

%T -6263313247,80914977953,1388589345953,1388589345953,-354298838750047,

%U -354298838750047,-121999399247582047,-121999399247582047

%N a(n) = Sum_{k=1..n} k!*mu(k), where mu() is the Moebius function.

%H Seiichi Manyama, <a href="/A099739/b099739.txt">Table of n, a(n) for n = 1..450</a>

%t f[n_] := Sum[k!MoebiusMu[k], {k, n}]; Table[ f[n], {n, 20}] (* _Robert G. Wilson v_, Nov 12 2004 *)

%o (PARI) a(n) = sum(k=1, n, moebius(k)*k!); \\ _Seiichi Manyama_, May 19 2021

%Y Cf. A002321.

%K sign

%O 1,3

%A _Leroy Quet_, Nov 09 2004

%E More terms from _Robert G. Wilson v_, Nov 12 2004