a(n) = Sum_{k=1..n} (-1)^(n-k) * k * mu(k)^2, where mu(k) is the Moebius function.

Terms

a(0) =1a(1) =1a(2) =2a(3) =-2a(4) =7a(5) =-1a(6) =8a(7) =-8a(8) =8a(9) =2a(10) =9a(11) =-9a(12) =22a(13) =-8a(14) =23a(15) =-23a(16) =40a(17) =-40a(18) =59a(19) =-59a(20) =80a(21) =-58a(22) =81a(23) =-81a(24) =81a(25) =-55a(26) =55a(27) =-55a(28) =84a(29) =-54