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

A360293

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

Terms

    a(0) =1a(1) =2a(2) =6a(3) =18a(4) =58a(5) =194a(6) =662a(7) =2290a(8) =8002a(9) =28178a(10) =99830a(11) =355426a(12) =1270586a(13) =4557682a(14) =16396454a(15) =59135458a(16) =213745922a(17) =774077986a(18) =2808105318a(19) =10202439858a(20) =37118386490a(21) =135210620194a(22) =493082387766

External references