a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5, starting 1,0,-1,1.

Terms

a(0) =1a(1) =0a(2) =-1a(3) =1a(4) =2a(5) =5a(6) =8a(7) =13a(8) =20a(9) =38a(10) =86a(11) =215a(12) =526a(13) =1230a(14) =2762a(15) =6115a(16) =13670a(17) =31294a(18) =73258a(19) =173644a(20) =412612a(21) =978074a(22) =2313060a(23) =5472523a(24) =12989654a(25) =30974176a(26) =74174934a(27) =178173000a(28) =428776280a(29) =1033084378