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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A276545 Numbers k such that (43*10^k - 421)/9 is prime.

Original entry on oeis.org

2, 5, 7, 8, 11, 13, 25, 26, 61, 82, 131, 289, 377, 547, 845, 929, 1786, 5887, 6562, 10546, 28033, 33493, 150515, 205183
Offset: 1

Views

Author

Robert Price, Apr 09 2017

Keywords

Comments

For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 7 followed by the digits 31 is prime (see Example section).
a(25) > 3*10^5.

Examples

			4 is in this sequence because (43*10^4 - 421)/9 = 477731 is prime.
Initial terms and associated primes:
a(1) = 2, 431;
a(2) = 5, 477731;
a(3) = 7, 47777731;
a(4) = 8, 477777731;
a(5) = 11, 477777777731; etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[1, 100000], PrimeQ[(43*10^# - 421)/9] &]

Extensions

a(23) from Robert Price, Jan 21 2019
a(24) from Robert Price, Oct 25 2023

A276546 Numbers k such that (151*10^k - 1)/3 is prime.

Original entry on oeis.org

1, 3, 6, 15, 19, 34, 37, 88, 141, 216, 239, 246, 288, 365, 429, 762, 1879, 2309, 9555, 19843, 28348, 45058, 62879, 86963, 90669, 148020, 148601, 199003, 289877
Offset: 1

Views

Author

Robert Price, Apr 09 2017

Keywords

Comments

Numbers k such that the digits 50 followed by k occurrences of the digit 3 is prime (see Example section).
a(30) > 3*10^5.

Examples

			3 is in this sequence because (151*10^3 - 1)/3 = 50333 is prime.
Initial terms and associated primes:
a(1) = 1, 503;
a(2) = 3, 50333;
a(3) = 6, 50333333;
a(4) = 15, 50333333333333333;
a(5) = 19, 503333333333333333333; etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(151*10^# - 1)/3] &]

Extensions

a(26)-a(28) from Robert Price, Mar 17 2020
a(29) from Robert Price, Oct 25 2023

A276642 Numbers k such that 3*10^k + 89 is prime.

Original entry on oeis.org

2, 3, 4, 5, 6, 8, 10, 14, 15, 62, 98, 184, 190, 389, 430, 815, 918, 1124, 1284, 9544, 10068, 16514, 24756, 39880, 86478, 179138
Offset: 1

Views

Author

Robert Price, Mar 23 2017

Keywords

Comments

For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 89 is prime (see Example section).
a(27) > 2*10^5.

Examples

			3 is in this sequence because 3*10^3 + 89 = 3089 is prime.
Initial terms and associated primes:
a(1) = 2, 389;
a(2) = 3, 3089;
a(3) = 4, 30089;
a(4) = 5, 300089;
a(5) = 6, 3000089; etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[3*10^# + 89] &]
  • PARI
    isok(k) = ispseudoprime(3*10^k + 89); \\ Altug Alkan, Mar 30 2018

Extensions

a(26) from Robert Price, Oct 22 2018

A276672 Numbers k such that (19*10^k + 101) / 3 is prime.

Original entry on oeis.org

1, 3, 4, 9, 10, 12, 13, 16, 20, 37, 57, 66, 106, 116, 127, 355, 396, 547, 2289, 3777, 4500, 7821, 15663, 22746, 25978, 30434, 39682, 119716, 133390, 145093, 200260
Offset: 1

Views

Author

Robert Price, Sep 12 2016

Keywords

Comments

For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 3 followed by the digits 67 is prime (see Example section).
a(32) > 3*10^5. - Robert Price, Jul 13 2023

Examples

			3 is in this sequence because (19*10^3 + 101) / 3 = 6367 is prime.
Initial terms and associated primes:
a(1) = 1, 97;
a(2) = 3, 6367;
a(3) = 4, 63367;
a(4) = 9, 6333333367;
a(5) = 10, 63333333367, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Magma
    [n: n in [0..400] |IsPrime((19*10^n + 101) div 3)]; // Vincenzo Librandi, Sep 13 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(19*10^# + 101) / 3] &]
  • PARI
    is(n)=ispseudoprime((19*10^n + 101)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(28)-a(30) from Robert Price, Sep 01 2019
a(31) from Robert Price, Jul 13 2023

A276673 Numbers k such that 94*10^k - 3 is prime.

Original entry on oeis.org

1, 2, 3, 4, 8, 19, 23, 25, 28, 65, 171, 183, 187, 295, 351, 471, 561, 634, 710, 1726, 3947, 4247, 6009, 11065, 13567, 94493, 147871, 182291
Offset: 1

Views

Author

Robert Price, Nov 16 2016

Keywords

Comments

For k > 0, numbers k such that the digits 93 followed by k-1 occurrences of the digit 9 followed by the digit 7 is prime (see Example section).
a(29) > 2*10^5.

Examples

			3 is in this sequence because 94*10^n - 3 = 93997 is prime.
Initial terms and associated primes:
a(1) = 1, 937;
a(2) = 2, 9397;
a(3) = 3, 93997;
a(4) = 4, 939997;
a(5) = 8, 9399999997, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[94*10^# - 3] &]
  • PARI
    is(n)=ispseudoprime(94*10^n - 3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(27)-a(28) from Robert Price, May 03 2020

A276698 Numbers k such that (25*10^k - 37) / 3 is prime.

Original entry on oeis.org

1, 2, 7, 17, 24, 32, 66, 67, 74, 92, 104, 117, 188, 260, 279, 336, 348, 369, 547, 619, 860, 2735, 7932, 11874, 14867, 40153, 171849, 176715
Offset: 1

Views

Author

Robert Price, Sep 14 2016

Keywords

Comments

For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 3 followed by the digits 21 is prime (see Example section).
a(29) > 2*10^5.

Examples

			2 is in this sequence because (25*10^2 - 37) / 3 = 821 is prime.
Initial terms and associated primes:
a(1) = 1, 71;
a(2) = 2, 821;
a(3) = 7, 83333321;
a(4) = 17, 833333333333333321;
a(5) = 24, 8333333333333333333333321, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(25*10^# - 37) / 3] &]
  • PARI
    is(n)=ispseudoprime((25*10^n - 37)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(27)-a(28) from Robert Price, Oct 07 2019

A276845 Numbers k such that (25*10^k - 73) / 3 is prime.

Original entry on oeis.org

1, 2, 5, 6, 40, 47, 49, 58, 67, 142, 170, 173, 232, 530, 539, 559, 1651, 1858, 2695, 6257, 6714, 8854, 15066, 15091, 16890, 51366, 85249, 135906
Offset: 1

Views

Author

Robert Price, Sep 20 2016

Keywords

Comments

For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 3 followed by the digits 09 is prime (see Example section).
a(29) > 2*10^5.

Examples

			2 is in this sequence because (25*10^2 - 73) / 3 = 809 is prime.
Initial terms and associated primes:
a(1) = 1, 59;
a(2) = 2, 809;
a(3) = 5, 833309;
a(4) = 6, 8333309;
a(5) = 40, 83333333333333333333333333333333333333309, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Magma
    [n: n in [0..500] | IsPrime((25*10^n - 73) div 3)]; // Vincenzo Librandi, Sep 22 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(25*10^# - 73) / 3] &]
  • PARI
    is(n) = ispseudoprime((25*10^n - 73) / 3); \\ Altug Alkan, Sep 20 2016

Extensions

a(28) from Robert Price, Sep 22 2019

A276846 Numbers k such that (4*10^k + 143) / 3 is prime.

Original entry on oeis.org

1, 2, 3, 4, 7, 9, 15, 21, 22, 44, 49, 53, 63, 127, 145, 393, 856, 1006, 1883, 2263, 5684, 13324, 14291, 27435, 38897, 114076
Offset: 1

Views

Author

Robert Price, Sep 20 2016

Keywords

Comments

For k > 1, numbers k such that the digit 1 followed by k-2 occurrences of the digit 3 followed by the digits 81 is prime (see Example section).
a(27) > 2*10^5.

Examples

			2 is in this sequence because (4*10^2 + 143) / 3 = 1381 is prime.
Initial terms and associated primes:
a(1) = 1, 61;
a(2) = 2, 181;
a(3) = 3, 1381;
a(4) = 4, 13381;
a(5) = 7, 13333381, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Magma
    [n: n in [0..500] | IsPrime((4*10^n+143) div 3)]; // Vincenzo Librandi, Sep 22 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(4*10^# + 143) / 3] &]
  • PARI
    is(n) = ispseudoprime((4*10^n + 143) / 3); \\ Altug Alkan, Sep 20 2016

Extensions

a(26) from Robert Price, Mar 05 2018

A277066 Numbers k such that (266*10^k - 11) / 3 is prime.

Original entry on oeis.org

1, 2, 3, 4, 7, 9, 10, 14, 28, 58, 93, 121, 135, 207, 350, 423, 602, 859, 1026, 1864, 1966, 13738, 23299, 28126, 38691, 39403, 47499, 93577, 124022, 177577
Offset: 1

Views

Author

Robert Price, Sep 27 2016

Keywords

Comments

For k > 0, numbers k such that the digits 88 followed by k-1 occurrences of the digit 6 followed by the digit 3 is prime (see Example section).
a(31) > 3*10^5.

Examples

			3 is in this sequence because (266*10^3 - 11) / 3 = 88663 is prime.
Initial terms and associated primes:
a(1) = 1, 883;
a(2) = 2, 8863;
a(3) = 3, 88663;
a(4) = 4, 886663;
a(5) = 7, 886666663, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(266*10^# - 11) / 3] &]
  • PARI
    is(n)=ispseudoprime((266*10^n - 11)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(29)-a(30) from Robert Price, Apr 01 2020

A278334 Numbers k such that (856*10^k - 1) / 9 is prime.

Original entry on oeis.org

2, 3, 5, 8, 9, 15, 20, 24, 41, 63, 66, 99, 281, 300, 462, 686, 726, 1196, 1574, 2543, 3023, 5322, 12161, 13677, 33797, 137633
Offset: 1

Views

Author

Robert Price, Nov 18 2016

Keywords

Comments

For k >= 0, numbers k such that the digits 95 followed by k occurrences of the digit 1 is prime (see Example section).
a(27) > 2*10^5.

Examples

			3 is in this sequence because (856*10^3 - 1) / 9 = 95111 is prime.
Initial terms and associated primes:
a(1) = 2, 9511;
a(2) = 3, 95111;
a(3) = 5, 9511111;
a(4) = 8, 9511111111;
a(5) = 9, 95111111111; etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(856*10^# - 1) / 9] &]
  • PARI
    is(n)=ispseudoprime((856*10^n - 1)/9) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(26) from Robert Price, Mar 30 2020
Previous Showing 101-110 of 490 results. Next

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