a(n) = Sum_{k=0..n} 8^k * binomial(k-2/3,k) * binomial(2*n-2/3,n-k).

A386959

a(n) = Sum_{k=0..n} 8^k * binomial(k-2/3,k) * binomial(2*n-2/3,n-k).

Terms

    a(0) =1a(1) =4a(2) =27a(3) =208a(4) =1724a(5) =14952a(6) =133581a(7) =1217976a(8) =11269359a(9) =105423292a(10) =994691555a(11) =9449623872a(12) =90277420688a(13) =866526247552

External references