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.

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A138066 Least k > 0 such that (2n-1)^k + 2 is prime, or 0 if no such number exists.

Original entry on oeis.org

1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 11, 0, 1, 1, 0, 2, 1, 0, 1, 1, 0, 1, 113, 0, 1, 7, 0, 1, 1, 0, 3, 1, 0, 1, 1, 0, 12, 1, 0, 1, 3, 0, 1, 255, 0, 8, 1, 0, 1, 1, 0, 1, 1, 0, 1, 3, 0, 2, 15, 0, 2, 1, 0, 1, 23, 0, 1, 1, 0, 4, 3, 0, 1, 1, 0, 3, 1, 0, 136, 1, 0, 1
Offset: 1

Views

Author

Alexander Adamchuk, Mar 02 2008

Keywords

Comments

a(3n+1) = 0 for n > 0.
a(84) > 100000. - Ray Chandler, Aug 10 2011

Crossrefs

Cf. A084713 (smallest prime of the form (2n-1)^k + 2, or 0 if no such number exists).
Cf. A138067 (least k > 1 such that (2n-1)^k + 2 is prime, or 0 if no such number exists).
Cf. A051783 (k such that 3^k + 2 is prime).
Cf. A087885 (k such that 5^k + 2 is prime).
Cf. A090649, A109076, A113480, A138048, A138049, A138050, A138051, A087886, A113481.

A138067 Least k > 1 such that (2n-1)^k + 2 is prime, or 0 if no such number exists.

Original entry on oeis.org

2, 2, 3, 0, 2, 5, 0, 2, 105, 0, 2, 11, 0, 5, 3, 0, 2, 15, 0, 2, 9, 0, 2, 113, 0, 5, 7, 0, 2, 27, 0, 3, 3, 0, 3, 3, 0, 12, 61, 0, 2, 3, 0, 4, 255, 0, 8, 63, 0, 2, 9, 0, 2, 3473, 0, 2, 3, 0, 2, 15, 0, 2, 87, 0, 3, 23, 0, 36, 1861, 0, 4, 3, 0, 2, 5, 0, 3, 7, 0, 136, 425, 0, 11
Offset: 1

Views

Author

Alexander Adamchuk, Mar 02 2008

Keywords

Comments

a(3n+1) = 0 for n > 0.
a(84) > 100000. - Ray Chandler, Aug 10 2011

Crossrefs

Cf. A084713 (smallest prime of the form (2n-1)^k + 2, or 0 if no such number exists).
Cf. A138066 (least k > 0 such that (2n-1)^k + 2 is prime, or 0 if no such number exists).
Cf. A051783 (k such that 3^k + 2 is prime).
Cf. A087885 (k such that 5^k + 2 is prime).
Cf. A090649, A109076, A113480, A138048, A138049, A138050, A138051, A087886, A113481.

Extensions

a(54)-a(83) from Donovan Johnson, Oct 29 2008

A217134 Numbers n such that 5^n - 8 is prime.

Original entry on oeis.org

2, 4, 10, 14, 88, 112, 140, 764, 3040, 11096, 24934, 25616, 54584, 93400
Offset: 1

Views

Author

Vincenzo Librandi, Oct 01 2012

Keywords

Comments

a(15) > 10^5. - Robert Price, Feb 03 2014

Crossrefs

Cf. A059613, A087885, A089142, A109080, A124621, A165701.

Programs

  • Mathematica
    Select[Range[2, 5000], PrimeQ[5^# - 8] &]
  • PARI
    for(n=2, 5*10^3, if(isprime(5^n-8), print1(n", ")))

Extensions

a(10)-a(14) from Robert Price, Feb 03 2014

A248547 Numbers n such that 75^n+2 is prime.

Original entry on oeis.org

0, 12, 28, 53, 65, 504, 1967, 6915
Offset: 1

Views

Author

Vaclav Kotesovec, Oct 08 2014

Keywords

Comments

Dedicated to N. J. A. Sloane for his 75th birthday!
Next term, if it exists, is greater than 10000.
Next term, if it exists, is greater than 50000. - Michael S. Branicky, May 21 2025

Crossrefs

Cf. A051783, A087885, A090649, A109076, A138048, A113480, A138049, A138050.

Programs

  • Magma
    [n: n in [0..200] | IsPrime(75^n+2)]; // Vincenzo Librandi, Oct 08 2014
  • Mathematica
    Select[Range[0, 1000], PrimeQ[75^# + 2] &]
  • PARI
    is(n)=ispseudoprime(75^n+2) \\ Charles R Greathouse IV, Jun 13 2017
Previous Showing 11-14 of 14 results.

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

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