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 1-8 of 8 results.

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

A096305 Numbers k such that 7^k + 4 is prime.

Original entry on oeis.org

0, 1, 2, 3, 5, 7, 9, 14, 23, 129, 198, 235, 275, 630, 870, 1033, 1290, 3293, 3458, 11466, 13885, 25893, 32186, 33139, 58125, 78929, 97197, 121933, 128422, 442674
Offset: 1

Views

Author

Herman H. Rosenfeld (herm3(AT)pacbell.net), Jun 26 2004

Keywords

Examples

			7^14 + 4 = 678223072853 is a prime number.

Crossrefs

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

Programs

  • Mathematica
    Do[If[PrimeQ[7^n+4], Print[n]], {n, 1, 1000}]
  • PARI
    for(n=0, 10^5, if(ispseudoprime(7^n+4), print1(n, ", "))) \\  Felix Fröhlich, Jun 04 2014

Extensions

More terms (probable primes) from Rick L. Shepherd, Jun 29 2004
7 more terms from Jason Earls, Feb 16 2008
a(25)-a(27) from Robert Price, Jan 24 2014
a(28)-a(29) from Lelio R. Paula, Nov 2014
a(30) from Paul Bourdelais, Feb 11 2021

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

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, ", ")))

A291862 Primes of the form 7^k + 12.

Original entry on oeis.org

13, 19, 61, 40353619, 59768263894155949306790119265585619217025149412430681661, 3945286644626550630858717985746264080026751644458455916464504975630931364915053228398031941487628933218072924433889392982611734440563298413
Offset: 1

Views

Author

Robert Price, Sep 04 2017

Keywords

Links

Crossrefs

Cf. A152213.

Programs

  • Mathematica
    Select[Table[7^k+12, {k, 0, 100}], PrimeQ[#] &]
Showing 1-8 of 8 results.

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

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