a(1)=1, a(n) = n*a(floor(n/2)).

Terms

a(0) =1a(1) =2a(2) =3a(3) =8a(4) =10a(5) =18a(6) =21a(7) =64a(8) =72a(9) =100a(10) =110a(11) =216a(12) =234a(13) =294a(14) =315a(15) =1024a(16) =1088a(17) =1296a(18) =1368a(19) =2000a(20) =2100a(21) =2420a(22) =2530a(23) =5184a(24) =5400a(25) =6084a(26) =6318a(27) =8232a(28) =8526a(29) =9450