a(n) = Sum_{i=0..n/2}((binomial(2*i+1,i)*binomial(2*n+2,n-2*i))/(2*i+1)).
A270560
a(n) = Sum_{i=0..n/2}((binomial(2*i+1,i)*binomial(2*n+2,n-2*i))/(2*i+1)).
Terms
- a(0) =1a(1) =4a(2) =16a(3) =64a(4) =257a(5) =1036a(6) =4191a(7) =17008a(8) =69221a(9) =282468a(10) =1155493a(11) =4737720a(12) =19468217a(13) =80167548a(14) =330792264a(15) =1367637504a(16) =5665322405a(17) =23512490804a(18) =97763764907a(19) =407238803064
External references
- oeis: A270560