A145074 Coefficient of x^(4^n) in Q(x)^(n+1) where Q(x) = Sum_{k>=0} (x^(4^k) + x^(2*4^k) + x^(3*4^k)).
1, 3, 12, 97, 885, 10386, 141295, 2218987, 39171564, 770029605, 16652860169, 393052609026, 10051000032099, 276818387211471, 8168772682637220, 257133140827399753
Offset: 0
Programs
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PARI
{a(n,q=4)=local(Q=sum(j=0,n,(x^(q^j)-x^(q*q^j))/(1-x^(q^j)+O(x^(q^n+1)))));polcoeff(Q^(n+1),q^n)}
Extensions
a(8)-a(10) from Sean A. Irvine, Mar 31 2011
a(11)-a(15) from Max Alekseyev, Dec 19 2011