a(n) = (1/(2*n+1)) * Sum_{k=0..n} (k+1)^4 * (2*k+1) * binomial(3*n-k,n-k).
A390970
a(n) = (1/(2*n+1)) * Sum_{k=0..n} (k+1)^4 * (2*k+1) * binomial(3*n-k,n-k).
Terms
- a(0) =1a(1) =17a(2) =132a(3) =865a(4) =5377a(5) =32844a(6) =199728a(7) =1215665a(8) =7422675a(9) =45505785a(10) =280185936a(11) =1732542012a(12) =10757286316a(13) =67050368440a(14) =419438982936
External references
- oeis: A390970