a(n)=Product{k=0..n, 1+2^A101650(k)}/2.

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =60a(5) =180a(6) =900a(7) =1800a(8) =3600a(9) =18000a(10) =54000a(11) =162000a(12) =486000a(13) =2430000a(14) =4860000a(15) =9720000a(16) =29160000a(17) =58320000a(18) =116640000a(19) =583200000a(20) =1749600000a(21) =5248800000a(22) =10497600000a(23) =31492800000a(24) =62985600000a(25) =188956800000