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 11 results. Next

A090669 Numbers k such that 7^k - 2 is a prime.

Original entry on oeis.org

1, 2, 4, 7, 8, 12, 15, 28, 31, 84, 98, 128, 238, 302, 859, 1508, 1586, 2091, 2796, 2888, 3924, 4815, 5636, 6596, 7090, 20176, 22176, 56386, 84050, 115515, 245608, 259710, 274120
Offset: 1

Views

Author

Herman H. Rosenfeld (herm3(AT)pacbell.net), Dec 16 2003

Keywords

Examples

			7^12 - 2 = 13841287199 a prime number.

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

Extensions

Corrected and extended by Robert G. Wilson v and Ray Chandler, Dec 22 2003
Three more terms from Ryan Propper, Dec 07 2008
a(28)-a(30) from Robert Price, Jan 24 2014
a(31)-a(32) from Paul Bourdelais, Jan 29 2021
a(33) from Paul Bourdelais, Aug 02 2023

A191469 Numbers n such that 7^n - 6 is prime.

Original entry on oeis.org

2, 3, 6, 9, 21, 25, 33, 49, 54, 133, 245, 255, 318, 1023, 1486, 3334, 6821, 8555, 11605, 42502, 44409, 90291, 92511, 140303
Offset: 1

Views

Author

Vincenzo Librandi, Jun 06 2011

Keywords

Comments

a(14)=1023 and a(15)=1486 correspond to BPSW strong probable primes (passing PARI's ispseudoprime()). - Joerg Arndt, Jun 06 2011
a(25) > 2*10^5. - Robert Price, Nov 14 2014

Crossrefs

Cf. A014224, A059266, A059613, A059614, A095714, A177093.
Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

  • Magma
    [n: n in [1..1000]| IsPrime(7^n-6)]
  • Maple
    A191469:=n->`if`(isprime(7^n-6),n,NULL): seq(A191469(n), n=1..10^3); # Wesley Ivan Hurt, Nov 14 2014
  • Mathematica
    Select[Range[1,5000],PrimeQ[7^#-6]&] (* Vincenzo Librandi, Aug 05 2012 *)
  • PARI
    for(n=1, 10^6, if(isprime(7^n-6), print1(n, ", ")))

Extensions

a(17)-a(23) from Robert Price, Jan 24 2014
a(24) from Robert Price, Nov 14 2014

A217130 Numbers n such that 7^n + 6 is prime.

Original entry on oeis.org

0, 1, 3, 16, 36, 244, 315, 2577, 9500, 17596, 25551, 32193, 32835, 36504, 75136
Offset: 1

Views

Author

Vincenzo Librandi, Oct 01 2012

Keywords

Comments

a(16) > 10^5. - Robert Price, Jan 24 2014

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

  • Magma
    /* The code produces the sequence up to 315: */ [n: n in [0..2000] | IsPrime(7^n+6)];
  • Mathematica
    Select[Range[0, 5000], PrimeQ[7^# + 6] &]
  • PARI
    for(n=1, 5000, if(isprime(7^n+6), print1(n", ")))

Extensions

a(9)-a(15) from Robert Price, Jan 24 2014

A217131 Numbers n such that 7^n - 8 is prime.

Original entry on oeis.org

2, 4, 8, 10, 50, 106, 182, 293, 964, 1108, 1654, 1756, 4601, 8870, 15100, 17446, 22742, 34570, 50150, 95276
Offset: 1

Views

Author

Vincenzo Librandi, Oct 01 2012

Keywords

Comments

a(21) > 10^5. - Robert Price, Jan 23 2014

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

  • Mathematica
    Select[Range[1, 5000], PrimeQ[7^#  - 8] &]
  • PARI
    for(n=1, 5*10^3, if(isprime(7^n-8), print1(n, ", ")))

Extensions

a(14)-a(20) from Robert Price, Jan 23 2014

A104065 Primes of the form 7^k + 4.

Original entry on oeis.org

5, 11, 53, 347, 16811, 823547, 40353611, 678223072853, 27368747340080916347
Offset: 1

Views

Author

Roger L. Bagula, Mar 02 2005

Keywords

Links

Crossrefs

Cf. A096305.

Programs

  • Mathematica
    a = Delete[Union[Flatten[Table[If [PrimeQ[7^n + 3 + 1] == True, 7^n + 3 + 1, 0], {n, 1, 400}]]], 1]
Select[7^Range[0,30]+4,PrimeQ] (* Harvey P. Dale, Jul 31 2021 *)

Formula

a(n) = 7^A096305(n) + 4. - Amiram Eldar, Jun 05 2025

Extensions

Initial 5 from Vincenzo Librandi, Dec 10 2010

A152213 Numbers n such that 7^n + 12 is prime.

Original entry on oeis.org

0, 1, 2, 9, 66, 164, 221, 224, 2058, 3224, 12284, 13457, 22277, 22761, 83381
Offset: 1

Views

Author

Huseyin Azoguz (huseyin(AT)mmnetz.de), Nov 29 2008

Keywords

Comments

a(16) > 10^5. - Robert Price, Jan 24 2014

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

Extensions

a(11)-a(15) from Robert Price, Jan 24 2014

A217132 Numbers n such that 7^n + 10 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 7, 11, 26, 29, 41, 53, 55, 84, 86, 144, 179, 229, 238, 414, 616, 1158, 4111, 5577, 13237, 15244, 48578, 66074
Offset: 1

Views

Author

Vincenzo Librandi, Oct 01 2012

Keywords

Comments

a(29) > 10^5. - Robert Price, Jan 24 2014

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

  • Mathematica
    Select[Range[0, 3000], PrimeQ[7^# + 10] &]
  • PARI
    for(n=1, 3*10^3, if(isprime(7^n+10), print1(n", ")))

Extensions

a(23)-a(28) from Robert Price, Jan 24 2014

A236371 Numbers n such that 7^n - 12 is prime.

Original entry on oeis.org

2, 3, 4, 12, 27, 28, 34, 36, 147, 179, 242, 276, 278, 466, 735, 2371, 4548, 5606, 10324, 82899
Offset: 1

Views

Author

Robert Price, Jan 23 2014

Keywords

Comments

a(21) > 10^5.

Crossrefs

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Programs

  • Mathematica
    Select[Range[1, 100000], PrimeQ[7^# - 12] &]
  • PARI
    for(n=1, 5*10^5, if(isprime(7^n-12), print1(n, ", ")))

A243397 Numbers n such that 19^n+4 is prime.

Original entry on oeis.org

0, 1, 3, 21, 145, 273, 1425, 9613, 15711, 18445
Offset: 1

Views

Author

Felix Fröhlich, Jun 04 2014

Keywords

Comments

No further terms up to 20000. - Felix Fröhlich, Oct 29 2014
No further terms up to 24000. - Felix Fröhlich, Jan 22 2015
No further terms up to 50000. - Michael S. Branicky, Oct 09 2024

Crossrefs

Corresponding sequences for k^n+4: A058958 (k=3), A124621 (k=5), A096305 (k=7), A217384 (k=9), A137236 (k=13).

Programs

  • Magma
    [n: n in [0..1000] | IsPrime(19^n+4)]; // Vincenzo Librandi, Oct 16 2014
  • Mathematica
    Select[Range[0, 10000], PrimeQ[19^# + 4] &] (* Vincenzo Librandi, Oct 16 2014 *)
  • PARI
    for(n=0, 10^5, if(ispseudoprime(19^n+4), print1(n, ", ")))

Extensions

a(1)-a(2) prepended by N. J. A. Sloane, Jun 18 2014
a(9)-a(10) from Felix Fröhlich, Oct 16 2014

A247166 Numbers k such that 15^k+4 is prime.

Original entry on oeis.org

0, 1, 2, 7, 10, 39, 42, 201, 225, 551
Offset: 1

Views

Author

Felix Fröhlich, Dec 01 2014

Keywords

Comments

No further terms up to 10000.
No further terms up to 10^5. - Tyler NeSmith, Jan 21 2021

Crossrefs

Corresponding sequences for m^k+4: A058958 (m=3), A124621 (m=5), A096305 (m=7), A217384 (m=9), A137236 (m=13), A243397 (m=19).

Programs

  • Magma
    [n: n in [0..300] | IsPrime(15^n+4)]; // Vincenzo Librandi, Dec 01 2015
  • Mathematica
    a247166[n_Integer] := Select[Range[n], PrimeQ[15^# + 4] &]; a247166[10^4] (* Michael De Vlieger, Dec 03 2014 *)
  • PARI
    for(n=0, 1e5, if(ispseudoprime(15^n+4), print1(n, ", ")))

Extensions

Offset changed to 1 by Georg Fischer, Sep 26 2022
Showing 1-10 of 11 results. Next

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

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