a(n) = Pell(n) * Sum_{d|n} (-1)^(n/d) / Pell(d), where Pell(n) = A000129(n).

Terms

a(0) =1a(1) =-1a(2) =6a(3) =-17a(4) =30a(5) =-48a(6) =170a(7) =-645a(8) =1183a(9) =-1270a(10) =5742a(11) =-22604a(12) =33462a(13) =-40868a(14) =240756a(15) =-746637a(16) =1136690a(17) =-1884529a(18) =6625110a(19) =-23217030a(20) =46565244a(21) =-46627416a(22) =225058682a(23) =-975425316a(24) =1356970471a(25) =-1583502622a(26) =9182205852a(27) =-26257649200a(28) =44560482150a(29) =-77433044928