OFFSET
0,2
FORMULA
a(n) ~ sin(Pi/7) * 2^(2*n) * 7^(3*n) / (Pi*n)^(3/2). - Vaclav Kotesovec, Oct 23 2020
EXAMPLE
G.f.: A(x) = 1 + 84*x + 45864*x^2 + 35672000*x^3 +...
A(x)^(1/2) = 1 + 42*x + 22050*x^2 + 16909900*x^3 +...+ A184895(n)*x^n +...
PROG
(PARI) {a(n)=(2*n)!/n!^2*(7^n/n!^2)*prod(k=0, n-1, (7*k+1)*(7*k+6))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 25 2011
STATUS
approved