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A284671
Numbers n > 2 such that A258409(n)*A002322(n) divides n-1.
1
1729, 41041, 75361, 172081, 449065, 656601, 670033, 1050985, 2433601, 2704801, 3664585, 4903921, 6840001, 7995169, 8355841, 8719921, 9582145, 9613297, 9890881, 10402561, 11205601, 12945745, 13992265, 15888313, 16778881, 17586361, 17812081, 19683001, 20964961
OFFSET
1,1
COMMENTS
A proper subset of the Carmichael numbers A002997.
If n is in the sequence, then n-1 is not squarefree.
Problem: are there infinitely many such numbers?
LINKS
MATHEMATICA
Select[Range[3, 10^6], Divisible[#-1, CarmichaelLambda[#] * GCD @@ (Divisors[#] - 1)] &] (* Amiram Eldar, Jun 26 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Thomas Ordowski and Altug Alkan, Apr 01 2017
STATUS
approved