a(2*n) = A000217(n), a(2*n+1) = -2*A000217(n).

Terms

a(0) =0a(1) =0a(2) =1a(3) =-2a(4) =3a(5) =-6a(6) =6a(7) =-12a(8) =10a(9) =-20a(10) =15a(11) =-30a(12) =21a(13) =-42a(14) =28a(15) =-56a(16) =36a(17) =-72a(18) =45a(19) =-90a(20) =55a(21) =-110a(22) =66a(23) =-132a(24) =78a(25) =-156a(26) =91a(27) =-182a(28) =105a(29) =-210