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 10 results.

A271884 Numbers n such that 4^n-3^(n-1) is prime.

Original entry on oeis.org

1, 2, 4, 6, 10, 12, 30, 42, 54, 166, 264, 886, 1476, 8412, 9576, 12426, 24076
Offset: 1

Views

Author

Robert Price, Apr 16 2016

Keywords

Comments

a(18) > 10^5.

Examples

			4 is a member since 4^4 - 3^3 =  256 - 27 = 229 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[4^# - 3^(# - 1)] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime(4^n-3^(n-1)), print1(n, ", "))); \\ Altug Alkan, Apr 16 2016

A272345 Numbers n such that 8^n-7^(n-1) is prime.

Original entry on oeis.org

1, 3, 5, 29, 41, 83, 471, 725, 1277, 10271, 15069, 97731
Offset: 1

Views

Author

Robert Price, Apr 26 2016

Keywords

Comments

a(13) > 10^5.

Examples

			5 is a member since 8^5 - 7^4 = 32768 - 2401 = 30367 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[8^# - 7^(# - 1)] &]
  • PARI
    is(n)=ispseudoprime(8^n-7^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017

A272272 Numbers k such that 4^k-3^(k+1) is prime.

Original entry on oeis.org

4, 8, 24, 36, 48, 246, 608, 734, 774, 824, 948, 1244, 3230, 4656, 5448, 6360, 7598, 15390, 48158, 86754
Offset: 1

Views

Author

Robert Price, Apr 24 2016

Keywords

Comments

a(21) > 10^5.

Examples

			8 is a member since 4^8 - 3^9 = 65536-19683 = 45853 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883.

Programs

  • Mathematica
    Select[Range[4, 100000], PrimeQ[4^# - 3^(# + 1)] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime(4^n-3^(n+1)), print1(n, ", "))); \\ Altug Alkan, Apr 24 2016

Extensions

Typo in a(11) corrected by Georg Fischer, Mar 19 2022

A272296 Numbers n such that 5^n-4^(n-1) is prime.

Original entry on oeis.org

3, 11, 25, 341, 1827, 2581, 4475, 11157, 41141, 64721
Offset: 1

Views

Author

Robert Price, Apr 27 2016

Keywords

Comments

a(11) > 10^5.

Examples

			3 is a member since 5^3 - 4^2 = 125 - 16 = 109 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884, A272345.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[5^# - 4^(# - 1)] &]
  • PARI
    is(n)=ispseudoprime(5^n-4^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017

A272366 Numbers n such that 5^n-4^(n+1) is prime.

Original entry on oeis.org

7, 25, 29, 55, 75, 243, 345, 635, 899, 2025, 2105, 2295, 5057, 5155, 5209, 11115, 81743, 97615
Offset: 1

Views

Author

Robert Price, Apr 27 2016

Keywords

Comments

a(19) > 10^5.

Examples

			7 is a member since 5^7 - 4^8 = 78125 - 65536 = 12589 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[5^# - 4^(# + 1)] &]
  • PARI
    is(n)=ispseudoprime(5^n-4^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017

A272781 Numbers n such that 6^n-5^(n+1) is prime.

Original entry on oeis.org

9, 14, 32, 48, 78, 85, 108, 134, 834, 1701, 2275, 3103, 5795, 10307, 17243, 24045, 31085, 32613, 40014
Offset: 1

Views

Author

Robert Price, May 06 2016

Keywords

Comments

a(20) > 10^5.

Examples

			9 is a member since 6^9 - 5^10 = 10077696 - 9765625 = 312071 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[6^# - 5^(# + 1)] &]
  • PARI
    is(n)=ispseudoprime(6^n-5^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017

A273868 Numbers k such that 10^k - 9^(k+1) is prime.

Original entry on oeis.org

25, 51, 91, 107, 145, 651, 1473, 2145, 5577, 12457
Offset: 1

Views

Author

Robert Price, Jun 01 2016

Keywords

Comments

a(11) > 10^5.

Examples

			25 is a term since 10^25 - 9^26 = 3538918110773326701067759, which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883.

Programs

  • Mathematica
    Select[Range[21, 100000], PrimeQ[10^# - 9^(# + 1)] &]
  • PARI
    is(n)=ispseudoprime(10^n-9^(n+1)) \\ Charles R Greathouse IV, Jun 08 2016

A274693 Numbers n such that 4^n + 3^(n+1) is prime.

Original entry on oeis.org

1, 2, 4, 5, 9, 10, 12, 17, 18, 29, 30, 40, 58, 82, 113, 129, 164, 192, 252, 524, 624, 766, 977, 1742, 2208, 2440, 3052, 4742, 5480, 16572, 17501
Offset: 1

Views

Author

Robert Price, Jul 02 2016

Keywords

Comments

a(32) > 10^5.

Examples

			5 is a member since 4^5 + 3^6 = 1024 + 729 = 1753 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883.

Programs

  • Magma
    [n: n in [1..700] | IsPrime(4^n + 3^(n+1))]; // Vincenzo Librandi, Jul 03 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[4^# + 3^(# + 1)] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime(4^n + 3^(n+1)), print1(n, ", "))); \\ Altug Alkan, Jul 02 2016

A274711 Numbers n such that 5^n + 4^(n+1) is prime.

Original entry on oeis.org

0, 2, 6, 34, 282, 3662, 87206
Offset: 1

Views

Author

Robert Price, Jul 03 2016

Keywords

Comments

a(8) > 10^5.

Examples

			6 is a member since 5^6 + 4^7 = 15625 + 16384 = 32009 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[5^# + 4^(# + 1)] &]
  • PARI
    lista(nn) = for(n=0, nn, if(ispseudoprime(5^n + 4^(n+1)), print1(n, ", "))); \\ Altug Alkan, Jul 03 2016

A275783 Numbers n such that 10^n + 9^(n+1) is prime.

Original entry on oeis.org

2, 3, 6, 11, 44, 64, 83, 123, 166, 381, 446, 1221, 1540, 3156, 5117, 5476, 6291, 6353, 13053, 15158, 23904, 78288, 82254, 91230
Offset: 1

Views

Author

Robert Price, Aug 08 2016

Keywords

Comments

a(25) > 10^5.

Examples

			3 is a member since 10^3 + 9^4 = 1000 + 6561 = 7561 which is a prime number.

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[10^# + 9^(# + 1)] &]
  • PARI
    is(n)=ispseudoprime(10^n+9^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017
Showing 1-10 of 10 results.

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

Content is available under The OEIS End-User License Agreement.