A236373 - OEIS

A236373

Pseudoprimes to base 2 of the form 6p+1 such that 2^(p-1) == 1 (mod p).

2047, 8388607, 140737488355327, 576460752303423487

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OFFSET

1,1

COMMENTS

The first four terms are A065341(1), A065341(2), A065341(7), A065341(9) and have the form 2^m-1. Are there terms not of this form?

Composite 2^n-1 belong to this sequence when n is in A005385 (e.g., 2^83-1, 2^167-1, etc.)

No other terms below 2^64. - Max Alekseyev, May 28 2014

LINKS

EXAMPLE

2047=6*341+1; 2^2046 == 1 (mod 2047); 2^340 == 1 (mod 341).

CROSSREFS

Subsequence of A001567.

KEYWORD

nonn,more

AUTHOR

EXTENSIONS

a(4) from Max Alekseyev, May 28 2014

STATUS

approved