a(n) = Sum_{k=0..n} C(n,k) * C(3*n+k,k).
A156886
a(n) = Sum_{k=0..n} C(n,k) * C(3*n+k,k).
Terms
- a(0) =1a(1) =5a(2) =43a(3) =416a(4) =4239a(5) =44485a(6) =475780a(7) =5156548a(8) =56437231a(9) =622361423a(10) =6904185523a(11) =76964141600a(12) =861408728964
External references
- oeis: A156886