Number of subsequences of [ 1,...,n ] in which each even number has an odd neighbor.

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =11a(5) =25a(6) =39a(7) =89a(8) =139a(9) =317a(10) =495a(11) =1129a(12) =1763a(13) =4021a(14) =6279a(15) =14321a(16) =22363a(17) =51005a(18) =79647a(19) =181657a(20) =283667a(21) =646981a(22) =1010295a(23) =2304257a(24) =3598219a(25) =8206733a(26) =12815247a(27) =29228713a(28) =45642179a(29) =104099605