OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..500
Index entries for linear recurrences with constant coefficients, signature (85,-1428,5440,-4096).
FORMULA
a(n) = [x^(4^n)] Product_{j=1..4} 1/(1-x^j).
G.f.: -(2048*x^4+1460*x^3-1067*x^2+80*x-1) / ((1-x) *(1-4*x) *(1-4^2*x) *(1-4^3*x)).
a(n) = (128 + 9*2^(3+2*n) + 15*16^n + 64^n)/144 for n > 0. - Stefano Spezia, Oct 08 2022
MAPLE
gf:= -(2048*x^4+1460*x^3-1067*x^2+80*x-1)/((1-x)*(1-4*x)*(1-4^2*x)*(1-4^3*x)):
a:= n-> coeff(series(gf, x, n+1), x, n):
seq(a(n), n=0..20);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Mar 01 2014
STATUS
approved