a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n,k) * binomial(n+2,k).
A388409
a(n) = Sum_{k=0..n} 3^(n-k) * binomial(n,k) * binomial(n+2,k).
Terms
- a(0) =1a(1) =6a(2) =39a(3) =262a(4) =1794a(5) =12444a(6) =87139a(7) =614646a(8) =4360590a(9) =31081780a(10) =222412902a(11) =1596770652a(12) =11495992708a(13) =82967270520a(14) =600053409915
External references
- oeis: A388409