a(n) = Sum_{k=0..n} binomial(3*n+1,k) * binomial(2*n-k-1,n-k).
A386937
a(n) = Sum_{k=0..n} binomial(3*n+1,k) * binomial(2*n-k-1,n-k).
Terms
- a(0) =1a(1) =5a(2) =38a(3) =325a(4) =2934a(5) =27314a(6) =259356a(7) =2496813a(8) =24281510a(9) =237978598a(10) =2346750900a(11) =23257207714a(12) =231438363324
External references
- oeis: A386937