a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-3,n-3*k).
A390707
a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-3,n-3*k).
Terms
- a(0) =1a(1) =0a(2) =3a(3) =21a(4) =132a(5) =828a(6) =5226a(7) =33201a(8) =212163a(9) =1362585a(10) =8788392a(11) =56890089a(12) =369422505a(13) =2405404014a(14) =15699336705a(15) =102678479961a(16) =672789288276
External references
- oeis: A390707