a(n) = Sum_{k=0..n} 2^k * 3^(n-k) * binomial(k+2,2) * binomial(k,n-k)^2.
A391678
a(n) = Sum_{k=0..n} 2^k * 3^(n-k) * binomial(k+2,2) * binomial(k,n-k)^2.
Terms
- a(0) =1a(1) =6a(2) =42a(3) =368a(4) =2616a(5) =18672a(6) =132112a(7) =906624a(8) =6151536a(9) =41243552a(10) =273427680a(11) =1797219840a(12) =11722297600a(13) =75943488000a(14) =489123171840
External references
- oeis: A391678