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

Offset: 1

Author

Jon E. Schoenfield, Sep 08 2018

Keywords

• nonn

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.

Examples

			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).
		

Links

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

Crossrefs

Cf. A000129 (Pell numbers), A094394, A319040, A319041, A319043.