Numerator of 2^n*(3*n-3)!/( ((n-1)!)^3 * (2*n)! ).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =11a(5) =91a(6) =17a(7) =323a(8) =4807a(9) =3289a(10) =8671a(11) =11687a(12) =15283a(13) =10743949a(14) =15189721a(15) =21069613a(16) =1339779509a(17) =1339779509a(18) =101007559a(19) =101007559a(20) =4215217889a(21) =185371558793a(22) =8059632991a(23) =11489264051a(24) =815737747621