a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-2,n-3*k).
A390705
a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-2,n-3*k).
Terms
- a(0) =1a(1) =1a(2) =6a(3) =36a(4) =217a(5) =1332a(6) =8295a(7) =52221a(8) =331518a(9) =2118558a(10) =13611144a(11) =87833781a(12) =568893156a(13) =3696245515a(14) =24080248485a(15) =157245263196
External references
- oeis: A390705