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 1-10 of 33 results. Next

A377856 Numbers k such that (21^k + 2^k)/23 is prime.

Original entry on oeis.org

11, 17, 47, 2663
Offset: 1

Views

Author

Robert Price, Nov 09 2024

Keywords

Comments

The definition implies that k must be a prime.
a(5) > 10^5.

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[10000]], PrimeQ[(21^# + 2^#)/23] &]

A126856 Numbers n such that (31^n + 1)/32 is prime.

Original entry on oeis.org

109, 461, 1061, 50777
Offset: 1

Views

Author

Alexander Adamchuk, Mar 23 2007

Keywords

Comments

All terms are primes.
a(5) > 10^5. - Robert Price, Jul 12 2013

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (31^p + 1)/32 ], Print[p] ], {n,1,1100} ]
  • PARI
    is(n)=isprime((31^n+1)/32) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(4) from Robert Price, Jul 12 2013

A229145 Numbers k such that (36^k + 1)/37 is prime.

Original entry on oeis.org

31, 191, 257, 367, 3061, 110503, 1145393
Offset: 1

Views

Author

Robert Price, Sep 15 2013

Keywords

Comments

All such numbers k are prime.
Note that a(6) = 110503 corresponds to (36^110503 + 1)/37, which is only a probable prime with 171975 digits.
The primes corresponding to the terms of this sequence have 1 as their last digit and an even number as their next-to-last digit. - Iain Fox, Dec 08 2017

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (36^p + 1)/37 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=isprime((36^n+1)/37) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(6) = 110503 (posted by Lelio R. Paula on primenumbers.net) from Paul Bourdelais, Dec 08 2017
a(7) from Paul Bourdelais, Nov 03 2023

A185240 Numbers k such that (35^k + 1)/36 is prime.

Original entry on oeis.org

11, 13, 79, 127, 503, 617, 709, 857, 1499, 3823, 135623, 280979
Offset: 1

Views

Author

Robert Price, Aug 29 2013

Keywords

Comments

All terms are primes. a(11) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (35^p + 1)/36 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=isprime((35^n+1)/36) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(11)=135623 found as probable prime and added by Paul Bourdelais, Jul 05 2018
a(12) from Paul Bourdelais, Sep 13 2021

A229524 Numbers k such that (38^k + 1)/39 is prime.

Original entry on oeis.org

5, 167, 1063, 1597, 2749, 3373, 13691, 83891, 131591
Offset: 1

Views

Author

Robert Price, Sep 25 2013

Keywords

Comments

All terms are primes. a(9) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (38^p + 1)/39 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((38^n+1)/39) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(9)=131591 corresponds to a probable prime discovered by Paul Bourdelais, Jul 03 2018

A229663 Numbers n such that (40^n + 1)/41 is prime.

Original entry on oeis.org

53, 67, 1217, 5867, 6143, 11681, 29959
Offset: 1

Views

Author

Robert Price, Sep 27 2013

Keywords

Comments

All terms are primes.
a(8) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (40^p + 1)/41 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((40^n+1)/41) \\ Charles R Greathouse IV, Feb 17 2017

A230036 Numbers n such that (39^n + 1)/40 is prime.

Original entry on oeis.org

3, 13, 149, 15377
Offset: 1

Views

Author

Robert Price, Oct 05 2013

Keywords

Comments

All terms are primes.
a(5) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (39^p + 1)/40 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((39^n+1)/40) \\ Charles R Greathouse IV, Feb 17 2017

A231604 Numbers n such that (42^n + 1)/43 is prime.

Original entry on oeis.org

3, 709, 1637, 17911, 127609, 172663
Offset: 1

Views

Author

Robert Price, Nov 11 2013

Keywords

Comments

The first 5 terms are primes.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (42^p + 1)/43 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((42^n+1)/43) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

a(5)=127609 corresponds to a probable prime discovered by Paul Bourdelais, Jul 02 2018
a(6)=172663 corresponds to a probable prime discovered by Paul Bourdelais, Jul 29 2019

A231865 Numbers n such that (43^n + 1)/44 is prime.

Original entry on oeis.org

5, 7, 19, 251, 277, 383, 503, 3019, 4517, 9967, 29573
Offset: 1

Views

Author

Robert Price, Nov 14 2013

Keywords

Comments

All terms are primes.
a(11) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (43^p + 1)/44 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((43^n+1)/44) \\ Charles R Greathouse IV, Feb 20 2017

A235683 Numbers n such that (46^n + 1)/47 is prime.

Original entry on oeis.org

7, 23, 59, 71, 107, 223, 331, 2207, 6841, 94841
Offset: 1

Views

Author

Robert Price, Jan 13 2014

Keywords

Comments

All terms up to a(10) are primes.
a(11) > 10^5.

Crossrefs

Programs

  • Mathematica
    Do[ p=Prime[n]; If[ PrimeQ[ (46^p + 1)/47 ], Print[p] ], {n, 1, 9592} ]
  • PARI
    is(n)=ispseudoprime((46^n+1)/47) \\ Charles R Greathouse IV, May 22 2017
Showing 1-10 of 33 results. Next