a(n) = n * mu(n), where mu is the Möbius function A008683.

Terms

a(0) =1a(1) =-2a(2) =-3a(3) =0a(4) =-5a(5) =6a(6) =-7a(7) =0a(8) =0a(9) =10a(10) =-11a(11) =0a(12) =-13a(13) =14a(14) =15a(15) =0a(16) =-17a(17) =0a(18) =-19a(19) =0a(20) =21a(21) =22a(22) =-23a(23) =0a(24) =0a(25) =26a(26) =0a(27) =0a(28) =-29a(29) =-30