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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A271640 Numbers k such that 3*10^k + 73 is prime.

Original entry on oeis.org

1, 2, 5, 6, 13, 37, 50, 55, 71, 89, 217, 352, 355, 398, 449, 668, 742, 870, 1360, 1579, 2848, 3774, 5039, 5051, 6134, 6824, 7255, 12586, 17106, 27502, 30581, 33817, 97399, 170800, 172219, 177872
Offset: 1

Views

Author

Robert Price, Apr 11 2016

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 73 is prime (see Example section).
a(37) > 2*10^5.

Examples

			5 is in this sequence because 3*10^5 + 73 = 300073 is prime.
Initial terms and associated primes:
a(1) = 1, 103;
a(2) = 2, 373;
a(3) = 5, 300073;
a(4) = 6, 3000073;
a(5) = 13, 30000000000073, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[3*10^# + 73] &]
  • PARI
    is(n)=ispseudoprime(3*10^n + 73) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(34)-a(36) from Robert Price, Aug 10 2018

A271645 Numbers k such that (23*10^k + 91)/3 is prime.

Original entry on oeis.org

1, 2, 4, 15, 16, 19, 20, 26, 38, 47, 52, 75, 122, 191, 246, 257, 294, 305, 374, 592, 682, 729, 1092, 2053, 2997, 4065, 13936, 17214, 19059, 37433, 142105, 214633, 242909
Offset: 1

Views

Author

Robert Price, Apr 11 2016

Keywords

Comments

For k > 1, numbers k such that the digit 7 followed by k-2 occurrences of the digit 6 followed by the digits 97 is prime (see Example section).
a(34) > 3*10^5.

Examples

			4 is in this sequence because (23*10^4 + 91)/3 = 76697 is prime.
Initial terms and associated primes:
a(1) = 1, 107;
a(2) = 2, 797;
a(3) = 4, 76697;
a(4) = 15, 7666666666666697;
a(5) = 16, 76666666666666697, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(23*10^# + 91)/3] &]
  • PARI
    is(n)=ispseudoprime((23*10^n + 91)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(31) from Robert Price, Aug 11 2019
a(32)-a(33) from Robert Price, May 31 2023

A271646 Numbers k such that 22*10^k + 7 is prime.

Original entry on oeis.org

0, 1, 2, 9, 13, 14, 15, 17, 22, 23, 80, 297, 393, 524, 591, 1107, 1135, 1179, 1442, 2819, 3549, 3756, 3837, 4903, 5277, 5639, 7230, 13147, 14828, 16158, 18119, 28880, 99275, 212339, 254639
Offset: 1

Views

Author

Robert Price, Apr 11 2016

Keywords

Comments

For k > 1, numbers k such that the digits 22 followed by k-1 occurrences of the digit 0 followed by the digit 7 is prime (see Example section).
a(36) > 3*10^5.

Examples

			2 is in this sequence because 22*10^2+7 = 227 is prime.
Initial terms and associated primes:
a(1) = 0, 29;
a(2) = 1, 227;
a(3) = 2, 2207;
a(4) = 9, 22000000007;
a(5) = 13, 220000000000007, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[22*10^# + 7] &]
  • PARI
    is(n)=ispseudoprime(22*10^n + 7) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(34)-a(35) from Robert Price, Jun 01 2023

A271821 Numbers k such that (5*10^k - 143)/3 is prime.

Original entry on oeis.org

3, 4, 5, 6, 10, 23, 30, 33, 64, 189, 207, 213, 463, 547, 1225, 1795, 3726, 3947, 4989, 5226, 9825, 11489, 12666, 14512, 19588, 28795, 29903, 31889, 71357
Offset: 1

Views

Author

Robert Price, Apr 14 2016

Keywords

Comments

For k > 1, numbers k such that the digit 1 followed by k-2 occurrences of the digit 6 followed by the digits 19 is prime (see Example section).
a(31) > 2*10^5.

Examples

			4 is in this sequence because (5*10^4-143)/3 = 16619 is prime.
Initial terms and associated primes:
a(1) = 3, 1619;
a(2) = 4, 16619;
a(3) = 5, 166619;
a(4) = 6, 1666619;
a(5) = 10, 16666666619, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(5*10^#-143)/3] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((5*10^n-143)/3), print1(n, ", "))); \\ Altug Alkan, Apr 14 2016

A271822 Numbers k such that (91*10^k + 11)/3 is prime.

Original entry on oeis.org

1, 2, 4, 6, 12, 13, 14, 17, 19, 31, 50, 58, 81, 87, 161, 234, 244, 482, 505, 676, 1111, 1707, 1929, 2695, 3819, 7708, 28958, 44652, 51508, 56892, 158862, 160249, 162410
Offset: 1

Views

Author

Robert Price, Apr 14 2016

Keywords

Comments

Numbers k such that the digits 30 followed by k-1 occurrences of the digit 3 followed by the digit 7 is prime (see Example section).
a(34) > 3*10^5.

Examples

			4 is in this sequence because (91*10^4+11)/3 = 303337 is prime.
Initial terms and associated primes:
a(1) = 1, 307;
a(2) = 2, 3037;
a(3) = 4, 303337;
a(4) = 6, 30333337;
a(5) = 12, 30333333333337, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [1..300] |IsPrime((91*10^n + 11) div 3)]; // Vincenzo Librandi, Apr 15 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(91*10^# + 11)/3] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((91*10^n + 11)/3), print1(n, ", "))); \\ Altug Alkan, Apr 14 2016

Extensions

a(31)-a(33) from Robert Price, Feb 15 2020

A271882 Numbers k such that (10^k + 101)/3 is prime.

Original entry on oeis.org

1, 2, 3, 6, 9, 12, 23, 39, 59, 168, 198, 203, 231, 449, 863, 920, 1064, 1484, 1674, 2018, 2943, 3123, 4073, 4122, 8360, 11774, 16031, 26507, 31146, 33170, 44952, 62402, 88020, 89687
Offset: 1

Views

Author

Robert Price, Apr 16 2016

Keywords

Comments

For k > 1, numbers k such that k-2 occurrences of the digit 3 followed by the digits 67 is prime (see Example section).
a(35) > 2*10^5.

Examples

			3 is in this sequence because (10^3+101)/3 = 367 is prime.
Initial terms and associated primes:
a(1) = 1, 37;
a(2) = 2, 67;
a(3) = 3, 367;
a(4) = 6, 333367;
a(5) = 9, 333333367, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(10^#+101)/3] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((10^n+101)/3), print1(n, ", "))); \\ Altug Alkan, Apr 16 2016

A272059 Numbers k such that (17*10^k + 13)/3 is prime.

Original entry on oeis.org

1, 2, 4, 7, 10, 13, 15, 20, 22, 33, 34, 108, 117, 130, 193, 273, 280, 654, 775, 1144, 4014, 4015, 7701, 10356, 11478, 12427, 15075, 44107, 102597, 118635
Offset: 1

Views

Author

Robert Price, May 19 2016

Keywords

Comments

For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 6 followed by the digits 71 is prime (see Example section).
a(31) > 2*10^5.

Examples

			4 is in this sequence because (17*10^4 + 13)/3 = 56671 is prime.
Initial terms and associated primes:
a(1) = 1, 61;
a(2) = 2, 571:
a(3) = 4, 56671;
a(4) = 7, 56666671;
a(5) = 10, 56666666671, etc.

Links

Crossrefs

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

Programs

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

Extensions

a(29)-a(30) from Robert Price, Jan 22 2019

A272193 Numbers k such that (73*10^k + 143)/9 is prime.

Original entry on oeis.org

1, 2, 5, 7, 13, 16, 17, 25, 44, 52, 197, 233, 241, 389, 838, 856, 2252, 2945, 5207, 8020, 10708, 14663, 16885, 20366, 20450, 24121, 24437, 29348, 134939
Offset: 1

Views

Author

Robert Price, Apr 22 2016

Keywords

Comments

For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 1 followed by the digits 27 is prime (see Example section).
a(29) > 2*10^5.

Examples

			5 is in this sequence because (73*10^5 + 143)/9 = 811127 is prime.
Initial terms and associated primes:
a(1) = 1, 97;
a(2) = 2, 827;;
a(3) = 5, 811127;
a(4) = 7, 81111127;
a(5) = 13, 81111111111127, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(73*10^# + 143)/9] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((73*10^n + 143)/9), print1(n, ", "))); \\ Altug Alkan, Apr 22 2016

Extensions

a(29) from Robert Price, Jul 31 2019

A272195 Numbers k such that (64*10^k + 287)/9 is prime.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 13, 16, 22, 112, 134, 139, 250, 445, 475, 512, 544, 1318, 1588, 3307, 4216, 4457, 4474, 4979, 6241, 9551, 17939, 20405, 48106, 54467, 144797
Offset: 1

Views

Author

Robert Price, Apr 22 2016

Keywords

Comments

For k > 1, numbers k such that the digit 7 followed by k-2 occurrences of the digit 1 followed by the digits 43 is prime (see Example section).
a(32) > 2*10^5.

Examples

			5 is in this sequence because (64*10^5 + 287)/9 = 711143 is prime.
Initial terms and associated primes:
a(1) = 1, 103;
a(2) = 2, 743;
a(3) = 4, 71143;
a(4) = 5, 711143;
a(5) = 7, 71111143, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(64*10^#n + 287)/9] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((64*10^n + 287)/9), print1(n, ", "))); \\ Altug Alkan, Apr 22 2016

Extensions

a(31) from Robert Price, Apr 13 2019

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
Previous Showing 41-50 of 497 results. Next

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