OFFSET
0,2
FORMULA
a(2*n) == 1 (mod 3); a(2*n+1) == 2 (mod 3).
EXAMPLE
G.f.: A(x) = 1 + 2*x + 28*x^2 + 1592*x^3 + 320416*x^4 + 233502272*x^5 +...
where
A(x)^3 = 1 + 3*2*x + 6*2^4*x^2 + 10*2^9*x^3 + 15*2^16*x^4 + 21*2^25*x^5 +...
PROG
(PARI) {a(n)=polcoeff(sum(m=0, n, (m+1)*(m+2)/2*2^(m^2)*x^m+x*O(x^n))^(1/3), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 26 2011
STATUS
approved