A129981 - OEIS

%I #10 Aug 18 2015 00:40:14

%S 1,2,4,7,15,30,78,183,567,1512,5352,15747,61827,196962,842082,2869107,

%T 13191027,47650452,233445012,888174087,4604065287,18353375862,

%U 100102982262,416337125487,2378327679087,10284181259712,61295935653312

%N Sum of n!!, with n>=0.

%C Partial sums of A006882.

%e 0!!=1

%e 1!!=1 -> 1+1=2

%e 2!!=2 -> 2+2=4

%e 3!!=3 -> 4+3=7

%e 4!!=8 -> 7+8=15

%e 5!!=15 -> 15+15=30

%p A129981 := proc(n)

%p         add(doublefactorial(m),m=0..n) ;

%p end proc: # _R. J. Mathar_, Oct 11 2011

%t s = 0; lst = {}; Do[s += n!!; AppendTo[lst, s], {n, 0, 26, 1}]; lst (* _Zerinvary Lajos_, Jul 10 2009 *)

%K easy,nonn

%O 0,2

%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Jun 14 2007