A260377 Primes p such that A001221(p-1)^(p-1) == 1 (mod p^2).

3, 5, 17, 257, 1093, 3511, 65537, 1006003

Offset

1,1

Comments

No further terms up to 10^9.

The two known terms of A001220 are in the sequence, as is A014127(2), but not A014127(1).

No other terms below 2*10^14. - Max Alekseyev, Nov 05 2025

Links

Table of n, a(n) for n=1..8.

Example

A001221(1092) == 4 and 4^1092 == 1 (mod 1093^2), so 1093 is a term of the sequence.

Prog

(PARI) forprime(p=1, 1e9, if(Mod(omega(p-1), p^2)^(p-1)==1, print1(p, ", ")))

Crossrefs

Contains subsequence A019434.

Cf. A001220, A014127, A244546, A259502, A267487, A306909, A355545.

Sequence in context: A023394 A176689 A256510 * A056130 A273871 A078726

Adjacent sequences: A260374 A260375 A260376 * A260378 A260379 A260380

Keyword

nonn,hard,more

Author

Felix Fröhlich, Jul 23 2015

Status

approved