a(3n) = a(3n-1) + a(3n-2), a(3n+1) = 2n*a(3n) + a(3n-1), a(3n+2) = a(3n+1) + a(3n).

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =3a(5) =4a(6) =7a(7) =32a(8) =39a(9) =71a(10) =465a(11) =536a(12) =1001a(13) =8544a(14) =9545a(15) =18089a(16) =190435a(17) =208524a(18) =398959a(19) =4996032a(20) =5394991a(21) =10391023a(22) =150869313a(23) =161260336a(24) =312129649a(25) =5155334720a(26) =5467464369a(27) =10622799089a(28) =196677847971a(29) =207300647060