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A319042
Composite numbers k such that Pell(k) == 1 (mod k).
4
35, 169, 385, 899, 961, 1121, 2001, 3107, 4879, 4901, 5719, 6215, 6265, 6441, 6479, 6601, 7055, 7801, 8119, 8339, 9799, 10403, 10763, 10945, 13079, 13601, 15841, 18241, 19097, 20833, 20951, 22499, 24727, 27839, 29183, 29953, 30731, 31417, 31535, 34561, 37345
OFFSET
1,1
It appears that most of the terms of A319040 (Numbers k such that Pell(k) == 1 (mod k)) are primes; this sequence lists the composites.
For the composite numbers k such that Pell(k) == -1 (mod k), see A319043.
EXAMPLE
k=35 is in the sequence: Pell(35) = 8822750406821 = 35*252078583052 + 1 == 1 (mod 35).
k=6 is not in the sequence: Pell(6) = 70 = 6*12 - 2 !== 1 (mod 6).
CROSSREFS
Cf. A000129 (Pell numbers), A094394, A319040, A319041, A319043.
Sequence in context: A270860 A228453 A327651 * A033851 A219825 A194716
KEYWORD
nonn
AUTHOR
Jon E. Schoenfield, Sep 08 2018
STATUS
approved

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Last modified September 20 22:42 EDT 2024. Contains 376078 sequences. (Running on oeis4.)