[seqfan] Primary pretenders

[Tomasz Ordowski]

Dear SeqFans!

All distinct terms of the primary pretenders are

https://oeis.org/A108574

These numbers k < 561 are semiprimes k = pq such that p-1 | q-1, where
primes p <= q.

Cf. Seidov's comment and https://oeis.org/A121707

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Let a(n) be the smallest composite k not being a Carmichael number such
that n^k == n (mod k).

The sequence is unbounded. Yes?

Conjecture: The terms a(n) are all semiprimes k = pq such that p-1 | q-1,
as above.

Find the term a(10103) > 561. Cf. https://oeis.org/A000790

The terms a(n) such that A000790(n) = 561.

Best regards,

Thomas