A319042 - OEIS

A319042

Composite numbers k such that Pell(k) == 1 (mod k).

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

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OFFSET

1,1

COMMENTS

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.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..500

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