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 20 results. Next

A128344 Numbers k such that (7^k - 5^k)/2 is prime.

Original entry on oeis.org

3, 5, 7, 113, 397, 577, 7573, 14561, 58543, 100019, 123407, 136559, 208283, 210761, 457871, 608347, 636043
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
No other terms less than 10^5. - Robert Price, May 28 2012
No other terms less than 10^6. - Jon Grantham, Jul 29 2023

Links

Crossrefs

Cf. A062572, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Programs

  • Mathematica
    k=7; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((7^n-5^n)/2) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(7)-a(9) from Robert Price, May 28 2012
a(10)-a(17) from Jon Grantham, Jul 29 2023

A128336 Numbers k such that (6^k + 5^k)/11 is prime.

Original entry on oeis.org

3, 5, 17, 397, 409, 643, 1783, 2617, 4583, 8783
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
No other terms less than 100000. - Robert Price, May 11 2012

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128337, A128338, A128339, A128340, A128341, A128342, A128343, A004061, A082182, A121877, A059802, A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Mathematica
    k=6; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    forprime(p=3,1e4,if(ispseudoprime((6^p+5^p)/11),print1(p", "))) \\ Charles R Greathouse IV, Jul 16 2011

Extensions

a(7)-a(9) from Alexander Adamchuk, May 04 2010
One more term (8783) added (unknown discoverer) corresponding to a probable prime with 6834 digits by Jean-Louis Charton, Oct 06 2010

A128347 Numbers k such that (11^k - 5^k)/6 is prime.

Original entry on oeis.org

5, 41, 149, 229, 263, 739, 3457, 20269, 98221
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
a(10) > 10^5. - Robert Price, Jan 24 2013

Crossrefs

Cf. A062572, A128344, A128345, A128346, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Programs

  • Mathematica
    k=11; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((11^n-5^n)/6) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(7)-a(9) from Robert Price, Jan 24 2013

A128342 Numbers k such that (13^k + 5^k)/18 is prime.

Original entry on oeis.org

13, 19, 31, 359, 487, 757, 761, 1667, 2551, 3167, 6829
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
No other terms below 23600. - Max Alekseyev, Feb 01 2010
a(12) > 10^5. - Robert Price, Apr 30 2013

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128343. Cf. A004061, A082182, A121877, A059802. Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Mathematica
    k=13; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((13^n+5^n)/18) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

Four more terms from Max Alekseyev, Feb 01 2010

A128341 Numbers k such that (12^k + 5^k)/17 is prime.

Original entry on oeis.org

3, 5, 13, 347, 977, 1091, 4861, 4967, 34679
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
a(10) > 10^5. - Robert Price, May 05 2013

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128342, A128343.
Cf. A004061, A082182, A121877, A059802.
Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Mathematica
    k=12; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
Select[Range[1100],PrimeQ[(12^#+5^#)/17]&] (* Harvey P. Dale, Jul 24 2012 *)
  • PARI
    is(n)=isprime((12^n+5^n)/17) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

Two more terms (a(7) and a(8)) from Harvey P. Dale, Jul 24 2012
a(9) from Robert Price, May 05 2013

A128339 Numbers k such that (9^k + 5^k)/14 is prime.

Original entry on oeis.org

3, 5, 13, 17, 43, 127, 229, 277, 6043, 11131, 11821
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
a(12) > 10^5. - Robert Price, Dec 26 2012

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128340, A128341, A128342, A128343. Cf. A004061, A082182, A121877, A059802. Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Magma
    [n: n in [3..300] |IsPrime((9^n + 5^n) div 14)]; // Vincenzo Librandi, Nov 02 2018
  • Mathematica
    k=9; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((9^n+5^n)/14) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

3 more PRP terms from Sean A. Irvine, Oct 01 2009

A128340 Numbers k such that (11^k + 5^k)/16 is prime.

Original entry on oeis.org

7, 11, 181, 421, 2297, 2797, 4129, 4139, 7151, 29033
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
a(11) > 10^5. - Robert Price, Feb 09 2013

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128341, A128342, A128343.
Cf. A004061, A082182, A121877, A059802.
Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Mathematica
    k=11; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((11^n+5^n)/16) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(5)-a(10) from Robert Price, Feb 09 2013

A128348 Numbers k such that (12^k - 5^k)/7 is prime.

Original entry on oeis.org

2, 3, 31, 41, 53, 101, 421, 1259, 4721, 45259
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
Primality of the primes formed by a(8) and a(9) were certified by Primo. - Ray G. Opao, Jul 01 2012
a(11) > 10^5. - Robert Price, Mar 02 2013

Crossrefs

Cf. A062572, A128344, A128345, A128346, A128347, A128349, A128350, A128351, A128352, A128353, A128354.
Cf. A004061, A082182, A121877, A059802.
Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Programs

  • Mathematica
    k=12; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((12^n-5^n)/7) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(8) and a(9) from Ray G. Opao, Jul 01 2012
a(10) from Robert Price, Mar 02 2013

A128337 Numbers k such that (7^k + 5^k)/12 is prime.

Original entry on oeis.org

11, 31, 173, 271, 547, 1823, 2111, 5519, 7793, 22963, 41077, 49739
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
a(13) > 10^5. - Robert Price, Nov 20 2012

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128338, A128339, A128340, A128341, A128342, A128343.
Cf. A004061, A082182, A121877, A059802.
Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Programs

  • Mathematica
    k=7; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
  • PARI
    is(n)=isprime((7^n+5^n)/12) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(6)-a(12) from Robert Price, Nov 20 2012

A128345 Numbers k such that (8^k - 5^k)/3 is prime.

Original entry on oeis.org

2, 19, 1021, 5077, 34031, 46099, 65707, 347437
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Comments

All terms are primes.
No further terms up to 5000 - Harvey P. Dale, Mar 23 2011
a(8) > 10^5 - Robert Price, Dec 22 2012
a(9) > 10^6 - Jon Grantham, Jul 29 2023

Links

Crossrefs

Cf. A062572, A128344, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.
Cf. A004061, A082182, A121877, A059802.
Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Programs

  • Mathematica
    k=8; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n,1,200}]
Select[Range[5000],PrimeQ[(8^#-5^#)/3]&]  (* Harvey P. Dale, Mar 23 2011 *)
  • PARI
    is(n)=isprime((8^n-5^n)/3) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(4)-a(7) from Robert Price, Dec 22 2012
a(8) from Jon Grantham, Jul 29 2023
Showing 1-10 of 20 results. Next

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