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

A383884

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

Terms

    a(0) =1a(1) =8a(2) =76a(3) =776a(4) =8236a(5) =89528a(6) =989080a(7) =11055248a(8) =124659148a(9) =1415338328a(10) =16157960776a(11) =185298481904

External references