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

Terms

a(0) =6a(1) =3a(2) =15a(3) =5a(4) =35a(5) =7a(6) =77a(7) =11a(8) =143a(9) =13a(10) =221a(11) =17a(12) =323a(13) =19a(14) =437a(15) =23a(16) =667a(17) =29a(18) =899a(19) =31a(20) =1147a(21) =37a(22) =1517a(23) =41a(24) =1763a(25) =43a(26) =2021a(27) =47a(28) =2491a(29) =53