A068034 Number of subsets of {1,2,3,...,n} that sum to 0 mod 13.

1, 1, 1, 1, 1, 2, 5, 10, 20, 39, 79, 158, 316, 632, 1262, 2522, 5042, 10082, 20164, 40330, 80660, 161320, 322638, 645278, 1290556, 2581112, 5162224, 10324444, 20648884, 41297764, 82595524, 165191048, 330382100, 660764200, 1321528400

Offset: 0

Author

Antti Karttunen, Feb 11 2002

Keywords

• nonn

Crossrefs

13th row of A068009.

Programs

Mathematica

Table[Count[Subsets[Range[n]], ?(Divisible[Total[#], 13]&)], {n,20}] (* _Harvey P. Dale, Feb 14 2012 *)

Formula

Empirical G.f.: -(2*x^13-x^10+x^9-x^6+x^4+x^3+x^2+x-1) / ((2*x-1)*(2*x^13-1)). [Colin Barker, Dec 22 2012]