login
a(n) = floor(( (n+1)/2 )^n) - n!.
3

%I #9 Jan 29 2024 15:38:34

%S 0,0,0,2,15,123,1118,11344,127831,1590245,21700716,322880256,

%T 5209007463,90661989607,1694616510154,33876697720832,721588072472639,

%U 16321494271570569,390811944752490542,9878354899591168000,262896868506265373394,7349159002086450661211

%N a(n) = floor(( (n+1)/2 )^n) - n!.

%C Theorem (Cauchy): ((n+1)/2)^n > n! for n >= 2.

%D D. S. Mitrinovic, Analytic Inequalities, Springer-Verlag, 1970; p. 192, 3.1.14.

%H Paolo Xausa, <a href="/A127610/b127610.txt">Table of n, a(n) for n = 0..420</a>

%t A127610[n_] := Floor[((n+1)/2)^n] - n!;

%t Array[A127610, 25, 0] (* _Paolo Xausa_, Jan 29 2024 *)

%Y Cf. A127426.

%K nonn

%O 0,4

%A _N. J. A. Sloane_, Apr 03 2007