a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-3*k-3,n-3*k).
A390708
a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-3*k-3,n-3*k).
Terms
- a(0) =1a(1) =1a(2) =10a(3) =85a(4) =725a(5) =6279a(6) =55081a(7) =488034a(8) =4358178a(9) =39163801a(10) =353741245a(11) =3208690588a(12) =29209183319a(13) =266705449726
External references
- oeis: A390708