Inverse square of A061554.

Terms

a(0) =1a(1) =-2a(2) =1a(3) =-1a(4) =-2a(5) =1a(6) =5a(7) =-3a(8) =-2a(9) =1a(10) =2a(11) =9a(12) =-5a(13) =-2a(14) =1a(15) =-13a(16) =9a(17) =13a(18) =-7a(19) =-2a(20) =1a(21) =-5a(22) =-33a(23) =20a(24) =17a(25) =-9a(26) =-2a(27) =1a(28) =34a(29) =-27