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Numbers of the form n!+n^3.
1

%I #5 May 21 2015 16:26:47

%S 2,10,33,88,245,936,5383,40832,363609,3629800,39918131,479003328,

%T 6227022997,87178293944,1307674371375,20922789892096,355687428100913,

%U 6402373705733832,121645100408838859,2432902008176648000

%N Numbers of the form n!+n^3.

%C Sum of the reciprocals = 0.6470299890164780452999873886..

%t Table[n!+n^3,{n,20}] (* _Harvey P. Dale_, May 21 2015 *)

%o (PARI) factncub(n) = {sr=0; for(x=1,n, y=x!+x^3; print1(y","); sr+=1.0/y; ); print(); print(sr) }

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Mar 02 2003