a(n) = (1/2)*( (1+(-1)^n)*A134762(n/2) + 2*(1-(-1)^n) ).

Terms

a(0) =1a(1) =2a(2) =4a(3) =2a(4) =16a(5) =2a(6) =58a(7) =2a(8) =208a(9) =2a(10) =754a(11) =2a(12) =2770a(13) =2a(14) =10294a(15) =2a(16) =38608a(17) =2a(18) =145858a(19) =2a(20) =554266a(21) =2a(22) =2116294a(23) =2a(24) =8112466a(25) =2a(26) =31201798a(27) =2a(28) =120349798a(29) =2