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

Terms

a(0) =1a(1) =1a(2) =3a(3) =5a(4) =11a(5) =17a(6) =39a(7) =61a(8) =139a(9) =217a(10) =495a(11) =773a(12) =1763a(13) =2753a(14) =6279a(15) =9805a(16) =22363a(17) =34921a(18) =79647a(19) =124373a(20) =283667a(21) =442961a(22) =1010295a(23) =1577629a(24) =3598219a(25) =5618809a(26) =12815247a(27) =20011685a(28) =45642179a(29) =71272673