Number of steps for aliquot sequence for n to converge to 0, or -1 if it never reaches 0.

Terms

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