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a(n) = ceiling(n!/e) with e = A001113 = exp(1).
0

%I #15 May 15 2017 16:04:54

%S 1,1,1,3,9,45,265,1855,14833,133497,1334961,14684571,176214841,

%T 2290792933,32071101049,481066515735,7697064251745,130850092279665,

%U 2355301661033953,44750731559645107,895014631192902121,18795307255050944541,413496759611120779881

%N a(n) = ceiling(n!/e) with e = A001113 = exp(1).

%D F. S. Roberts, Applied Combinatorics, Prentice-Hall, 1984, p. 263.

%F a(2n) = A000166(2n). a(2n+1) = A000166(2n+1)+1.

%t Table[Ceiling[n!*Exp[ -1]], {n, 0, 30}]

%o (PARI) a(n) = ceil(n!/exp(1)); \\ _Michel Marcus_, May 15 2017

%Y Cf. A000166.

%K nonn

%O 0,4

%A _Roger L. Bagula_, Mar 15 2010