A036687 a(n) = Product_{i=0..n} (3*i+1)! / (n+i)!.
1, 12, 420, 35280, 6486480, 2473511040, 1888413246720, 2815188363187200, 8043859365429888000, 43422645527382401280000, 437806134821131674998400000, 8167684917019434265210752000000, 279763767797866931083907001600000000, 17478686582471797472931336490014720000000
Offset: 0