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

A385514

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

Terms

    a(0) =1a(1) =7a(2) =64a(3) =643a(4) =6766a(5) =73162a(6) =805414a(7) =8979523a(8) =101060326a(9) =1145704162a(10) =13064219224a(11) =149674343518

External references