a(n) = Sum_{k=0..n} (k+3) * binomial(4*n-3*k+3,n-k)/(4*n-3*k+3).
A390810
a(n) = Sum_{k=0..n} (k+3) * binomial(4*n-3*k+3,n-k)/(4*n-3*k+3).
Terms
- a(0) =1a(1) =4a(2) =20a(3) =119a(4) =789a(5) =5605a(6) =41729a(7) =321343a(8) =2538402a(9) =20454598a(10) =167477778a(11) =1389362192a(12) =11652787785a(13) =98645677902a(14) =841765475559
External references
- oeis: A390810