a(n) = A047760(2n+1).

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =5a(5) =12a(6) =23a(7) =55a(8) =114a(9) =273a(10) =588a(11) =1428a(12) =3156a(13) =7752a(14) =17427a(15) =43263a(16) =98516a(17) =246675a(18) =567281a(19) =1430715a(20) =3316521a(21) =8414640a(22) =19633796a(23) =50067108a(24) =117464424a(25) =300830572a(26) =709098696a(27) =1822766520a(28) =4313876888a(29) =11124755664