OFFSET
1,2
COMMENTS
Reversion of g.f. for the cubes (A000578).
LINKS
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Series Reversion
FORMULA
G.f. A(x) satisfies: A(x)*(1 + 4*A(x) + A(x)^2)/(1 - A(x))^4 = x.
a(n) ~ -(-1)^n * (5*sqrt(6) - 12) * 2^(3*n-2) * 3^n / (sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Nov 11 2017
D-finite with recurrence 7*n*(n-1)*(n+1)*a(n) +4*n*(n-1)*(58*n-83)*a(n-1) -36*(n-1)*(16*n^2-80*n+155)*a(n-2) +432*(-96*n^3+720*n^2-1794*n+1495)*a(n-3) +6912*(4*n-15)*(2*n-7)*(4*n-13)*a(n-4)=0. - R. J. Mathar, Jan 25 2023
MATHEMATICA
Rest[CoefficientList[InverseSeries[Series[x (1 + 4 x + x^2)/(1 - x)^4, {x, 0, 19}], x], x]]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Aug 25 2017
STATUS
approved