Inverse Euler transform of the sum-of-divisors or sigma function A000203.

Terms

a(0) =1a(1) =2a(2) =1a(3) =0a(4) =-3a(5) =1a(6) =-1a(7) =1a(8) =3a(9) =-5a(10) =-1a(11) =4a(12) =3a(13) =-3a(14) =-7a(15) =8a(16) =1a(17) =-9a(18) =7a(19) =8a(20) =-13a(21) =-12a(22) =27a(23) =7a(24) =-19a(25) =-14a(26) =11a(27) =-17a(28) =-25a(29) =198