a(n) = Sum_{k=0..n} (-1)^k * binomial(-n,k) * binomial(3*k,n-k).
A362088
a(n) = Sum_{k=0..n} (-1)^k * binomial(-n,k) * binomial(3*k,n-k).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =55a(4) =369a(5) =2526a(6) =17577a(7) =123810a(8) =879921a(9) =6297643a(10) =45325764a(11) =327720471a(12) =2378598885a(13) =17319785588a(14) =126463925310a(15) =925620561780
External references
- oeis: A362088