A367003 a(n) is the largest prime factor of n*2^n-1.

1, 7, 23, 7, 53, 383, 179, 89, 271, 3413, 2503, 2137, 59, 367, 1433, 41, 15803, 59729, 26423, 11161, 1559, 12611, 9187523, 127867, 119837257, 11527, 2360833, 43969, 2339, 32212254719, 257503, 616318177, 260587, 127873, 682902239, 44939, 69660839431, 1185617

Offset: 1

Author

Sean A. Irvine, Oct 31 2023

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..865

Crossrefs

Cf. A003261, A006530, A005420, A367002, A367004, A366899.

Programs

Mathematica

a[n_] := FactorInteger[n*2^n - 1][[-1, 1]]; Array[a, 40] (* Amiram Eldar, Oct 29 2024 *)

Formula

a(n) = A006530(A003261(n)).