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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A272271 Numbers k such that 7*10^k - 23 is prime.

Original entry on oeis.org

1, 2, 3, 23, 29, 34, 35, 38, 52, 57, 61, 82, 186, 209, 251, 366, 394, 426, 786, 979, 1382, 2037, 4557, 8995, 12774, 19170, 21828, 23259, 32003, 41831, 44999, 56785, 76483, 97987, 110468
Offset: 1

Views

Author

Robert Price, Apr 24 2016

Keywords

Comments

For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 9 followed by the digits 77 is prime (see Example section).
a(36) > 3*10^5.

Examples

			3 is in this sequence because 7*10^3 - 23 = 6977 is prime.
Initial terms and associated primes:
a(1) = 1, 47;
a(2) = 2, 677;
a(3) = 3, 6977;
a(4) = 23, 699999999999999999999977;
a(5) = 29, 699999999999999999999999999977, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[7*10^# - 23] &]
  • PARI
    is(n)=ispseudoprime(7*10^n - 23) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(35) from Robert Price, Jul 27 2019

A272402 Numbers k such that (26*10^k - 131)/3 is prime.

Original entry on oeis.org

1, 2, 3, 5, 7, 10, 15, 20, 31, 107, 115, 290, 455, 611, 669, 1190, 2111, 2147, 2821, 4094, 4616, 7087, 7971, 11416, 12413, 21475, 23719, 24435, 32218, 122625, 160166, 190789
Offset: 1

Views

Author

Robert Price, Apr 28 2016

Keywords

Comments

For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 6 followed by the digits 23 is prime (see Example section).
a(33) > 2*10^5.

Examples

			3 is in this sequence because (26*10^3 - 131)/3 = 8623 is prime.
Initial terms and associated primes:
a(1) = 1, 43;
a(2) = 2, 823;
a(3) = 3, 8623;
a(4) = 5, 866623;
a(5) = 7, 86666623, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(26*10^# - 131)/3] &]
  • PARI
    isok(n) = isprime((26*10^n - 131)/3); \\ Michel Marcus, Apr 28 2016

Extensions

a(30)-a(32) from Robert Price, Oct 19 2019

A272523 Numbers k such that (265*10^k + 17)/3 is prime.

Original entry on oeis.org

2, 3, 4, 10, 35, 60, 65, 72, 87, 218, 226, 326, 365, 461, 611, 1244, 1566, 4839, 4913, 5396, 7020, 8410, 9714, 10362, 11405, 21695, 25240, 56076, 56588, 74579, 81990, 114736
Offset: 1

Views

Author

Robert Price, May 01 2016

Keywords

Comments

For k > 1, numbers k such that the digits 88 followed by k-1 occurrences of the digit 3 followed by the digit 9 is prime (see Example section).
a(33) > 2*10^5.

Examples

			3 is in this sequence because (265*10^3 + 17)/3 = 88339 is prime.
Initial terms and associated primes:
a(1) = 2, 8839;
a(2) = 3, 88339;
a(3) = 4, 883339;
a(4) = 10, 883333333339;
a(5) = 35, 8833333333333333333333333333333333339, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(265*10^# + 17)/3] &]
  • PARI
    is(n)=ispseudoprime((265*10^n + 17)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(32) from Robert Price, Mar 21 2020

A272537 Numbers k such that (28*10^k + 173)/3 is prime.

Original entry on oeis.org

0, 1, 2, 3, 9, 11, 13, 15, 17, 24, 37, 44, 48, 58, 65, 104, 393, 413, 1265, 2292, 2620, 3037, 3628, 5159, 5629, 12809, 18572, 26875, 29695, 32267, 34277, 43621, 138768, 220800
Offset: 1

Views

Author

Robert Price, May 02 2016

Keywords

Comments

For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 3 followed by the digits 91 is prime (see Example section).
a(35) > 3*10^5.

Examples

			3 is in this sequence because (28*10^3 + 173)/3 = 9391 is prime.
Initial terms and associated primes:
a(1) = 0, 67;
a(2) = 1, 151;
a(3) = 2, 991;
a(4) = 3, 9391;
a(5) = 9, 9333333391, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(28*10^# + 173)/3] &]
  • PARI
    is(n)=ispseudoprime((28*10^n + 173)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(33) from Robert Price, Dec 25 2019
a(34) from Robert Price, Jul 02 2024

A272622 Numbers k such that 9*10^k + 19 is prime.

Original entry on oeis.org

1, 2, 4, 5, 10, 14, 25, 34, 40, 63, 74, 129, 149, 345, 370, 425, 477, 627, 951, 1610, 2564, 2689, 4227, 7300, 7444, 8360, 16541, 21187, 25685, 31803, 89858, 92821
Offset: 1

Views

Author

Robert Price, May 03 2016

Keywords

Comments

For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 0 followed by the digits 19 is prime (see Example section).
a(33) > 3*10^5.

Examples

			4 is in this sequence because 9*10^4+19 = 90019 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 2, 919;
a(3) = 4, 90019;
a(4) = 5, 900019;
a(5) = 10, 90000000019, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[9*10^# + 19] &]
  • PARI
    is(n)=ispseudoprime(9*10^n + 19) \\ Charles R Greathouse IV, Jun 13 2017

A272717 Numbers k such that (65*10^k + 691)/9 is prime.

Original entry on oeis.org

1, 5, 7, 17, 35, 46, 56, 148, 187, 190, 256, 551, 553, 1033, 1751, 1976, 2696, 3116, 3364, 5353, 5893, 8063, 9548, 10640, 24655, 77992
Offset: 1

Views

Author

Robert Price, Aug 11 2016

Keywords

Comments

For k > 1, numbers k such that the digit 7 followed by k-2 occurrences of the digit 2 followed by the digits 99 is prime (see Example section).
a(27) > 10^5.

Examples

			5 is in this sequence because (65*10^5+691)/9 = 722299 is prime.
Initial terms and associated primes:
a(1) = 1, 149;
a(2) = 5, 722299;
a(3) = 7, 72222299;
a(4) = 17, 722222222222222299;
a(5) = 35, 722222222222222222222222222222222299, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(65*10^#+691)/9] &]
  • PARI
    is(n)=ispseudoprime((65*10^n+691)/9) \\ Charles R Greathouse IV, Jun 13 2017

A272830 Numbers k such that (8*10^k - 29)/3 is prime.

Original entry on oeis.org

1, 2, 3, 8, 9, 10, 16, 31, 35, 79, 179, 196, 239, 376, 515, 728, 812, 1154, 2000, 2379, 2485, 3523, 3987, 5221, 5257, 5739, 17863, 59127, 106454, 125894
Offset: 1

Views

Author

Robert Price, May 07 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 6 followed by the digits 57 is prime (see Example section).
a(31) > 2*10^5.

Examples

			3 is in this sequence because (8*10^3 - 29)/3 = 2657 is prime.
Initial terms and associated primes:
a(1) = 1, 17;
a(2) = 2, 257;
a(3) = 3, 2657;
a(4) = 8, 266666657;
a(5) = 9, 2666666657, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(8*10^# - 29)/3] &]
  • PARI
    is(n)=ispseudoprime((8*10^n-29)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(29)-a(30) from Robert Price, Jul 03 2018

A272929 Numbers k such that (8*10^k - 77)/3 is prime.

Original entry on oeis.org

2, 4, 5, 6, 15, 18, 43, 45, 55, 60, 105, 128, 180, 207, 271, 479, 869, 1220, 1478, 1937, 4003, 4213, 5503, 9562, 11388, 13120, 34049, 47178, 156371, 271039
Offset: 1

Views

Author

Robert Price, May 10 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 6 followed by the digits 41 is prime (see Example section).
a(31) > 3*10^5.

Examples

			4 is in this sequence because (8*10^4 - 77)/3 = 26641 is prime.
Initial terms and associated primes:
a(1) = 2, 241;
a(2) = 4, 26641;
a(3) = 5, 266641;
a(4) = 6, 2666641;
a(5) = 15, 2666666666666641, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[1, 100000], PrimeQ[(8*10^# - 77)/3] &]
  • PARI
    lista(nn) = {for(n=1, nn, if(ispseudoprime((8*10^n - 77)/3), print1(n, ", ")));} \\ Altug Alkan, May 11 2016

Extensions

a(29) from Robert Price, Jul 07 2018
a(30) from Robert Price, Jul 02 2023

A272999 Numbers k such that (11*10^k + 49)/3 is prime.

Original entry on oeis.org

1, 2, 4, 5, 7, 10, 11, 16, 18, 21, 22, 30, 41, 69, 83, 128, 166, 190, 262, 263, 353, 496, 1398, 1793, 2806, 9722, 15733, 32420, 61095, 77909, 110496
Offset: 1

Views

Author

Robert Price, May 12 2016

Keywords

Comments

For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 6 followed by the digits 83 is prime (see Example section).
a(32) > 3*10^5.

Examples

			4 is in this sequence because (11*10^4 + 49)/3 = 36683 is prime.
Initial terms and associated primes:
a(1) = 1, 53;
a(2) = 2, 383:
a(3) = 4, 36683;
a(4) = 5, 366683;
a(5) = 7, 36666683, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(11*10^# + 49)/3] &]
  • PARI
    is(n)=ispseudoprime((11*10^n + 49)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(31) from Robert Price, Jul 19 2018

A273006 Numbers k such that 88*10^k + 3 is prime.

Original entry on oeis.org

1, 2, 3, 7, 19, 21, 31, 50, 55, 151, 167, 287, 542, 603, 926, 1046, 2066, 2139, 2651, 2787, 5756, 6028, 6925, 10135, 13037, 36476, 74234, 119295
Offset: 1

Views

Author

Robert Price, Nov 09 2016

Keywords

Comments

For k > 0, numbers k such that the digits 88 followed by k-1 occurrences of the digit 0 followed by the digit 3 is prime (see Example section).
a(29) > 3*10^5.

Examples

			3 is in this sequence because 88*10^3 + 3 = 88003 is prime.
Initial terms and associated primes:
a(1) = 1, 883;
a(2) = 2, 8803;
a(3) = 3, 88003;
a(4) = 7, 880000003;
a(5) = 19, 880000000000000000003, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[88*10^# + 3] &] (* Corrected by Georg Fischer, Jul 22 2019 *)
  • PARI
    is(n)=ispseudoprime(88*10^n + 3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(28) from Robert Price, May 03 2020
Previous Showing 61-70 of 507 results. Next

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

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