login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 (list; graph; refs; listen; history; text; internal format)
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

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

Sequence in context: A270860 A228453 A327651 * A033851 A219825 A194716

Adjacent sequences:  A319039 A319040 A319041 * A319043 A319044 A319045

KEYWORD

nonn

AUTHOR

Jon E. Schoenfield, Sep 08 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 30 18:49 EST 2020. Contains 338808 sequences. (Running on oeis4.)