Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #13 Sep 08 2022 13:31:47
%S 1,1,1,1,1,2,5,10,20,39,79,158,316,632,1262,2522,5042,10082,20164,
%T 40330,80660,161320,322638,645278,1290556,2581112,5162224,10324444,
%U 20648884,41297764,82595524,165191048,330382100,660764200,1321528400
%N Number of subsets of {1,2,3,...,n} that sum to 0 mod 13.
%F 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]
%t Table[Count[Subsets[Range[n]], _?(Divisible[Total[#], 13]&)], {n,20}] (* _Harvey P. Dale_, Feb 14 2012 *)
%Y 13th row of A068009.
%K nonn
%O 0,6
%A _Antti Karttunen_, Feb 11 2002