a(n) = J(n) * J(n+2) where J(n) = Jacobsthal(n) = A001045(n).

Terms

a(0) =0a(1) =3a(2) =5a(3) =33a(4) =105a(5) =473a(6) =1785a(7) =7353a(8) =28985a(9) =116793a(10) =465465a(11) =1865273a(12) =7454265a(13) =29830713a(14) =119295545a(15) =477236793a(16) =1908837945a(17) =7635570233a(18) =30541844025a(19) =122168249913a(20) =488671252025