a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-1,n-3*k).
A371770
a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-3*k-1,n-3*k).
Terms
- a(0) =1a(1) =2a(2) =10a(3) =57a(4) =338a(5) =2057a(6) =12741a(7) =79914a(8) =505954a(9) =3226638a(10) =20696685a(11) =133382658a(12) =862978221a(13) =5601919325a(14) =36467212610a(15) =237974911737
External references
- oeis: A371770