a(n) = Product_{k = 1+n-floor(n/3) .. n} k.

Terms

a(0) =1a(1) =1a(2) =3a(3) =4a(4) =5a(5) =30a(6) =42a(7) =56a(8) =504a(9) =720a(10) =990a(11) =11880a(12) =17160a(13) =24024a(14) =360360a(15) =524160a(16) =742560a(17) =13366080a(18) =19535040a(19) =27907200a(20) =586051200a(21) =859541760a(22) =1235591280a(23) =29654190720a(24) =43609104000a(25) =62990928000