a(n) = Sum_{k=0..n} binomial(3*n+k-1,k) * binomial(n-1,n-k).
A378612
a(n) = Sum_{k=0..n} binomial(3*n+k-1,k) * binomial(n-1,n-k).
Terms
- a(0) =1a(1) =3a(2) =27a(3) =264a(4) =2703a(5) =28443a(6) =304740a(7) =3306852a(8) =36225519a(9) =399755001a(10) =4437142467a(11) =49485052224a(12) =554059164036
External references
- oeis: A378612