Fourth quadrisection of A140287.

Terms

a(0) =-1a(1) =2a(2) =-4a(3) =9a(4) =-25a(5) =82a(6) =-284a(7) =969a(8) =-3185a(9) =10082a(10) =-30964a(11) =93129a(12) =-276745a(13) =818482a(14) =-2421644a(15) =7188489a(16) =-21428705a(17) =64121282a(18) =-192388324a(19) =578087049a(20) =-1737827065a(21) =5223134482a(22) =-15690187004a(23) =47105428809a(24) =-141351839825a(25) =424023394082