a(n) = (n+3)*Sum_{i=0..n} binomial(3*n-2*i+2,n-i)/(2*n-i+3).
A277957
a(n) = (n+3)*Sum_{i=0..n} binomial(3*n-2*i+2,n-i)/(2*n-i+3).
Terms
- a(0) =1a(1) =5a(2) =26a(3) =144a(4) =834a(5) =4979a(6) =30361a(7) =188003a(8) =1177694a(9) =7443721a(10) =47384897a(11) =303389530a(12) =1951806313a(13) =12607088771a(14) =81709809546a(15) =531138264252
External references
- oeis: A277957