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A367003
a(n) is the largest prime factor of n*2^n-1.
4
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
1,2
LINKS
FORMULA
a(n) = A006530(A003261(n)).
MATHEMATICA
a[n_] := FactorInteger[n*2^n - 1][[-1, 1]]; Array[a, 40] (* Amiram Eldar, Oct 29 2024 *)
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Sean A. Irvine, Oct 31 2023
STATUS
approved