a(n) = Sum_{k=0..floor(n/2)} binomial(n-1-k,k) * binomial(2*n-4*k,n-2*k).

A360290

a(n) = Sum_{k=0..floor(n/2)} binomial(n-1-k,k) * binomial(2*n-4*k,n-2*k).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =22a(4) =82a(5) =314a(6) =1222a(7) =4814a(8) =19138a(9) =76626a(10) =308550a(11) =1248230a(12) =5069266a(13) =20654602a(14) =84392838a(15) =345659166a(16) =1418769154a(17) =5834283298a(18) =24031706246a(19) =99134911542a(20) =409495076050

External references