This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A068039 #6 Sep 08 2022 13:32:34
%S A068039 1,1,1,1,1,1,3,8,16,30,58,115,229,456,912,1824,3643,7286,14572,29132,
%T A068039 58262,116522,233024,466048,932096,1864150,3728300,7456600,14913112,
%U A068039 29826220,59652436,119304704,238609408,477218816,954437292,1908874584
%N A068039 Number of subsets of {1,2,3,...,n} that sum to 0 mod 18.
%F A068039 Empirical G.f.: -(12*x^35 +2*x^34 -16*x^33 +8*x^32 +16*x^31 -6*x^30 +2*x^29 +12*x^28 +16*x^27 -8*x^26 -32*x^25 -18*x^24 +6*x^23 +16*x^22 +6*x^21 +2*x^20 +12*x^19 -12*x^18 -6*x^17 -x^16 +8*x^15 -4*x^14 -8*x^13 +3*x^12 -x^11 -6*x^10 +4*x^8 +6*x^7 +x^6 +x^5 +x^4 -3*x^3 -x^2 -x +1) / ((2*x -1)*(2*x^3 -1)*(2*x^6 -1)*(2*x^9 -1)*(2*x^18 -1)). [_Colin Barker_, Dec 23 2012]
%Y A068039 18th row of A068009.
%K A068039 nonn
%O A068039 0,7
%A A068039 _Antti Karttunen_, Feb 11 2002