OFFSET
0,2
LINKS
Paul D. Hanna, Table of n, a(n) for n = 0..45
FORMULA
E.g.f.: ( Sum_{n>=0} 2^(n^2)*x^n/n! ) * ( Sum_{n>=0} 3^(n^2)*x^n/n! ).
a(n) ~ 3^(n^2). - Vaclav Kotesovec, Sep 03 2017
EXAMPLE
E.g.f.: A(x) = 1 + 5*x + 109*x^2/2! + 20825*x^3/3! + 43283641*x^4/4! + 847757178125*x^5/5! +...
where A(x) = B(x)*C(x) with
B(x) = 1 + 2*x + 2^4*x^2/2! + 2^9*x^3/3! + 2^16*x^4/4! + 2^25*x^5/5! +...
C(x) = 1 + 3*x + 3^4*x^2/2! + 3^9*x^3/3! + 3^16*x^4/4! + 3^25*x^5/5! +...
PROG
(PARI) {a(n)=sum(k=0, n, binomial(n, k)*2^((n-k)^2)*3^(k^2))}
for(n=0, 16, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 12 2014
STATUS
approved