Reversion of Euler totient function A000010.

Terms

a(0) =1a(1) =-1a(2) =0a(3) =3a(4) =-8a(5) =12a(6) =-6a(7) =-37a(8) =208a(9) =-730a(10) =1708a(11) =-1278a(12) =-10018a(13) =56782a(14) =-163644a(15) =229985a(16) =389830a(17) =-3724538a(18) =13460550a(19) =-28799694a(20) =12470564a(21) =205544596a(22) =-1084748334a(23) =3195484242a(24) =-4851317704a(25) =-7421547798a(26) =81343472008