A068013 Number of subsets of {1,2,3,...,n} that sum to 0 mod 7.

1, 1, 1, 1, 3, 5, 10, 20, 38, 74, 146, 294, 586, 1172, 2344, 4684, 9364, 18724, 37452, 74900, 149800, 299600, 599192, 1198376, 2396744, 4793496, 9586984, 19173968, 38347936, 76695856, 153391696, 306783376, 613566768, 1227133520, 2454267040

Offset: 0

Author

Antti Karttunen, Feb 11 2002

Keywords

• nonn

Crossrefs

7th row of A068009.

Formula

Empirical G.f.: -(2*x^7+x^5-x^4+x^3+x^2+x-1) / ((2*x-1)*(2*x^7-1)). [Colin Barker, Dec 22 2012]