A333986 Greatest prime factor of A007497(n).

2, 3, 2, 7, 2, 5, 3, 5, 7, 5, 7, 5, 127, 7, 8191, 5, 127, 13, 31, 127, 127, 89, 31, 17, 127, 31, 3221, 179, 151, 127, 8191, 13, 262657, 11939, 199, 257, 127, 127, 337, 257, 524287, 73, 1093, 547, 137, 241, 1093, 547, 331, 131071, 1093, 599479, 8191, 137, 127, 8191

Offset: 1

Author

Richard Peterson, Sep 04 2020

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A006530, A007497.

Programs

Mathematica

f[1] = 2; f[n_] := f[n] = DivisorSigma[1, f[n - 1]]; Table[FactorInteger[f[n]][[-1, 1]], {n, 50}] (* Amiram Eldar, Sep 23 2020 *)

Formula

a(n) = A006530(A007497(n)). - Michel Marcus, Sep 09 2020

Extensions

More terms from Michel Marcus, Sep 16 2020