a(n) = gcd(n, sigma(n)).

Terms

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