A129981 Sum of n!!, with n>=0.

1, 2, 4, 7, 15, 30, 78, 183, 567, 1512, 5352, 15747, 61827, 196962, 842082, 2869107, 13191027, 47650452, 233445012, 888174087, 4604065287, 18353375862, 100102982262, 416337125487, 2378327679087, 10284181259712, 61295935653312

Offset

0,2

Comments

Partial sums of A006882.

Links

Table of n, a(n) for n=0..26.

Example

0!!=1
1!!=1 -> 1+1=2
2!!=2 -> 2+2=4
3!!=3 -> 4+3=7
4!!=8 -> 7+8=15
5!!=15 -> 15+15=30

Maple

A129981 := proc(n)
        add(doublefactorial(m), m=0..n) ;
end proc: # R. J. Mathar, Oct 11 2011

Mathematica

s = 0; lst = {}; Do[s += n!!; AppendTo[lst, s], {n, 0, 26, 1}]; lst (* Zerinvary Lajos, Jul 10 2009 *)

Crossrefs

Sequence in context: A331934 A049885 A129682 * A358824 A072964 A247291

Adjacent sequences: A129978 A129979 A129980 * A129982 A129983 A129984

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Jun 14 2007

Status

approved