a(n) = Sum_{k=0..n} (2*k+3) * binomial(4*n-2*k+3,n-k)/(4*n-2*k+3).
A390811
a(n) = Sum_{k=0..n} (2*k+3) * binomial(4*n-2*k+3,n-k)/(4*n-2*k+3).
Terms
- a(0) =1a(1) =4a(2) =21a(3) =129a(4) =871a(5) =6255a(6) =46894a(7) =362852a(8) =2876277a(9) =23238219a(10) =190660664a(11) =1584290757a(12) =13305632458a(13) =112764573331a(14) =963162517251
External references
- oeis: A390811