The odd bisection of A000594.

Terms

a(0) =1a(1) =252a(2) =4830a(3) =-16744a(4) =-113643a(5) =534612a(6) =-577738a(7) =1217160a(8) =-6905934a(9) =10661420a(10) =-4219488a(11) =18643272a(12) =-25499225a(13) =-73279080a(14) =128406630a(15) =-52843168a(16) =134722224a(17) =-80873520a(18) =-182213314a(19) =-145589976a(20) =308120442a(21) =-17125708a(22) =-548895690a(23) =2687348496a(24) =-1696965207a(25) =-1740295368a(26) =-1596055698