a(n) = (3!)^3 * [z^3] hypergeom([], [1,1], z)^n.

Terms

a(0) =0a(1) =1a(2) =56a(3) =381a(4) =1192a(5) =2705a(6) =5136a(7) =8701a(8) =13616a(9) =20097a(10) =28360a(11) =38621a(12) =51096a(13) =66001a(14) =83552a(15) =103965a(16) =127456a(17) =154241a(18) =184536a(19) =218557a(20) =256520a(21) =298641a(22) =345136a(23) =396221a(24) =452112a(25) =513025a(26) =579176a(27) =650781a(28) =728056a(29) =811217