cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A074304 Numbers k such that Lucas(2k)/3 is prime.

Original entry on oeis.org

5, 7, 13, 19, 31, 43, 89, 101, 229, 293, 457, 541, 653, 659, 1553, 2003, 2707, 2749, 7159, 10289, 26267, 59581, 63421, 80911
Offset: 1

Views

Author

Shane Findley, Sep 21 2002

Keywords

Comments

Some of the larger entries may only correspond to probable primes.

Links

Crossrefs

Cf. A049685, A074281, A355980.

Formula

a(n) = 2*A355980(n) + 1. - Jinyuan Wang, Jul 22 2022

Extensions

More terms found by David Broadhurst, Bouk de Water, and Shane Findley, Oct 31 2002
a(22)-a(24) from Michael S. Branicky, Nov 05 2024

A355980 Indices of primes in A049685.

Original entry on oeis.org

2, 3, 6, 9, 15, 21, 44, 50, 114
Offset: 1

Views

Author

R. J. Mathar, Jul 22 2022

Keywords

Comments

Related to the search of solutions of the pair of congruences p^2 == -5 (mod q), q^2 == -5 (mod p).
Cosgrave and Dilcher list terms up to 25000, including probable primes.

Links

Crossrefs

Cf. A049685, A074281, A074304.

Formula

A074281(n) = A049685(a(n)).
a(n) = (A074304(n)-1)/2.
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.