A183035 G.f.: A(x) = x*(1-x^2)*Product_{n>=1} (1 + x^(4^n))^3.
1, 0, -1, 0, 3, 0, -3, 0, 3, 0, -3, 0, 1, 0, -1, 0, 3, 0, -3, 0, 9, 0, -9, 0, 9, 0, -9, 0, 3, 0, -3, 0, 3, 0, -3, 0, 9, 0, -9, 0, 9, 0, -9, 0, 3, 0, -3, 0, 1, 0, -1, 0, 3, 0, -3, 0, 3, 0, -3, 0, 1, 0, -1, 0, 3, 0, -3, 0, 9, 0, -9, 0, 9, 0, -9, 0, 3, 0, -3, 0, 9, 0, -9, 0, 27, 0, -27, 0, 27, 0, -27, 0, 9, 0
Offset: 1
Keywords
Examples
G.f.: A(x) = x - x^3 + 3*x^5 - 3*x^7 + 3*x^9 - 3*x^11 + x^13 - x^15 +...
Crossrefs
Cf. A183034.
Programs
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PARI
{a(n)=local(L4n=ceil(log(n+1)/log(4)));polcoeff(x*(1-x^2)*prod(k=1,L4n,1 + x^(4^k)+x*O(x^n))^3,n)}
Formula
a(2n) = 0.