a(1) = 1. For n > 1, a(n) = a(n-1)/2 if a(n-1) is even, a(n) = a(n-1)*n otherwise.

Terms

a(0) =1a(1) =2a(2) =1a(3) =4a(4) =2a(5) =1a(6) =7a(7) =56a(8) =28a(9) =14a(10) =7a(11) =84a(12) =42a(13) =21a(14) =315a(15) =5040a(16) =2520a(17) =1260a(18) =630a(19) =315a(20) =6615a(21) =145530a(22) =72765a(23) =1746360a(24) =873180a(25) =436590a(26) =218295a(27) =6112260a(28) =3056130a(29) =1528065