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Numbers k such that gcd(phi(k), k-1) > lambda(k)^2.
1

%I #28 Jul 24 2021 01:11:31

%S 432046225,631071001,4579461601,8494657921,53282340865,80601412609

%N Numbers k such that gcd(phi(k), k-1) > lambda(k)^2.

%C 2320690177 is the only 2 < k < 10^11 such that gcd(phi(k),k-1) = lambda(k)^2. - _Giovanni Resta_, Mar 24 2017

%Y Cf. A000010, A002322, A049559, A264012, A283656.

%K nonn,more

%O 1,1

%A _Thomas Ordowski_ and _Altug Alkan_, Mar 24 2017

%E a(3)-a(6) from _Giovanni Resta_, Mar 24 2017