a(n) = (1/(3^n)^2) * Sum_{k=0..(3^n-1)} binomial(2k,k).

A167912

a(n) = (1/(3^n)^2) * Sum_{k=0..(3^n-1)} binomial(2k,k).

Terms

    a(0) =1a(1) =217a(2) =913083596083

External references