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A236373
Pseudoprimes to base 2 of the form 6p+1 such that 2^(p-1) == 1 (mod p).
0
2047, 8388607, 140737488355327, 576460752303423487
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
EXAMPLE
2047=6*341+1; 2^2046 == 1 (mod 2047); 2^340 == 1 (mod 341).
CROSSREFS
Subsequence of A001567.
Sequence in context: A131952 A065341 A135976 * A289476 A353409 A222526
KEYWORD
nonn,more
AUTHOR
Alzhekeyev Ascar M, Jan 24 2014
EXTENSIONS
a(4) from Max Alekseyev, May 28 2014
STATUS
approved