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%I #9 Jun 22 2016 21:26:48
%S 1,2,3,6,11,19,26,34,44,54,65,77,90,104,119,135,152,170,189,209,230,
%T 252,275,299,324,350,377,405,434,464,495,527,560,594,629,665,702,740,
%U 779,819,860,902,945,989,1034,1080,1127,1175,1224,1274
%N Number of different coefficient values in expansion of Product (1+q^i+q^(2i)), i=1 to n.
%H Ray Chandler, <a href="/A039827/b039827.txt">Table of n, a(n) for n = 1..2500</a>
%F Conjectures from _Chai Wah Wu_, Jun 22 2016: (Start)
%F a(n) = n*(n+1)/2 - 1 for n >= 9.
%F a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 11.
%F G.f.: x*(-x^10 + 2*x^9 - x^8 - 2*x^7 + 4*x^6 - x^5 - 2*x^3 + x - 1)/(x - 1)^3. (End)
%t nmax = 50; d = {1}; a1 = {};
%t Do[
%t n0s = Table[0, {n}];
%t d = Join[d, n0s, n0s] + Join[n0s, d, n0s] + Join[n0s, n0s, d];
%t AppendTo[a1, Length[Union[d]]];
%t , {n, nmax}];
%t a1 (* _Ray Chandler_, Mar 26 2014 *)
%Y Cf. A039826.
%K nonn
%O 1,2
%A _Olivier Gérard_
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