a(n) = Sum_{k=0..floor(n/3)} (-1)^k * binomial(3*n-3*k-1,n-3*k).
A371816
a(n) = Sum_{k=0..floor(n/3)} (-1)^k * binomial(3*n-3*k-1,n-3*k).
Terms
- a(0) =1a(1) =2a(2) =10a(3) =55a(4) =322a(5) =1947a(6) =12013a(7) =75154a(8) =474946a(9) =3024742a(10) =19381045a(11) =124797862a(12) =806875421a(13) =5234713031a(14) =34060165282a(15) =222174355575
External references
- oeis: A371816