A129980 Sum of the digits of the sum of n!!, with n>=0.

1, 2, 4, 7, 6, 3, 15, 12, 18, 9, 15, 24, 24, 33, 24, 33, 24, 33, 24, 51, 42, 51, 33, 51, 69, 51, 60, 69, 60, 87, 60, 60, 87, 105, 87, 87, 105, 87, 87, 105, 114, 105, 96, 141, 123, 123, 159, 150, 159, 150, 141, 141, 132, 168, 159, 150, 177, 159, 159, 168, 195, 186, 195

Offset

0,2

Links

Table of n, a(n) for n=0..62.

Example

0!!=1
1!!=1 -> 1+1=2
2!!=2 -> 2+2=4
3!!=3 -> 4+3=7
4!!=8 -> 7+8=15 -> 1+5=6
5!!=15 -> 15+15=30 -> 3+0=3

Maple

P:=proc(n) local i, j, k, w, sf; sf:=1; for i from 0 by 1 to n do k:=i; w:=i-2; while w>0 do k:=k*w; w:=w-2; od; sf:=sf+k; w:=0; k:=sf; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; print(w); od; end: P(100);

Crossrefs

Sequence in context: A302991 A015791 A335818 * A198137 A126786 A154614

Adjacent sequences: A129977 A129978 A129979 * A129981 A129982 A129983

Keyword

easy,nonn,base

Author

Paolo P. Lava and Giorgio Balzarotti, Jun 14 2007

Status

approved