a(n) = (1/2) * Sum_{k=0..floor(n/3)} 2^(n-k) * binomial(2*n-4*k+2,2*k+1).
A387603
a(n) = (1/2) * Sum_{k=0..floor(n/3)} 2^(n-k) * binomial(2*n-4*k+2,2*k+1).
Terms
- a(0) =1a(1) =4a(2) =12a(3) =40a(4) =160a(5) =640a(6) =2416a(7) =8960a(8) =33664a(9) =127744a(10) =484096a(11) =1827840a(12) =6896896a(13) =26049536a(14) =98440192a(15) =371939328a(16) =1404997632a(17) =5307301888a(18) =20049424384a(19) =75742707712a(20) =286136467456
External references
- oeis: A387603