a(n) = Sum_{k=0..n} 3^k * 2^(n-k) * binomial(3*n+1,k) * binomial(3*n-k,n-k).
A386830
a(n) = Sum_{k=0..n} 3^k * 2^(n-k) * binomial(3*n+1,k) * binomial(3*n-k,n-k).
Terms
- a(0) =1a(1) =18a(2) =459a(3) =12942a(4) =382671a(5) =11632248a(6) =360048924a(7) =11287595862a(8) =357239123631
External references
- oeis: A386830