a(n) = A214938(2n+1).

Terms

a(0) =1a(1) =2a(2) =7a(3) =28a(4) =122a(5) =562a(6) =2693a(7) =13288a(8) =67064a(9) =344588a(10) =1796518a(11) =9479780a(12) =50532640a(13) =271710662a(14) =1471935235a(15) =8026070768a(16) =44015873308a(17) =242619318848