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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A275410 Numbers k such that (493*10^k - 7)/9 is prime.

Original entry on oeis.org

1, 2, 5, 7, 8, 14, 19, 22, 23, 31, 62, 65, 79, 178, 356, 401, 517, 557, 1040, 2248, 6718, 10730, 15079, 24938, 36241, 58486, 69340
Offset: 1

Views

Author

Robert Price, Jul 26 2016

Keywords

Comments

Numbers k such that the digits 54 followed by k occurrences of the digit 7 is prime (see Example section).
a(28) > 10^5.

Examples

			5 is in this sequence because (493*10^5-7)/9 = 5477777 is prime.
Initial terms and associated primes:
a(1) = 1, 547;
a(2) = 2, 5477;
a(3) = 5, 5477777;
a(4) = 7, 547777777;
a(5) = 8, 5477777777, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [0..500] | IsPrime((493*10^n-7) div 9)]; // Vincenzo Librandi, Jul 27 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(493*10^#-7)/9] &]
  • PARI
    is(n)=ispseudoprime((493*10^n-7)/9) \\ Charles R Greathouse IV, Jun 13 2017

A275522 Numbers k such that (28*10^k + 773)/9 is prime.

Original entry on oeis.org

0, 2, 5, 6, 11, 20, 32, 59, 81, 98, 128, 437, 758, 989, 998, 1403, 1548, 1907, 1914, 2219, 5414, 9047, 13196, 18518, 28382
Offset: 1

Views

Author

Robert Price, Jul 31 2016

Keywords

Comments

For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 1 followed by the digits 97 is prime (see Example section).
a(26) > 10^5.

Examples

			5 is in this sequence because (28*10^5 + 773)/9 = 311197 is prime.
Initial terms and associated primes:
a(1) = 0, 89;
a(2) = 2, 397;
a(3) = 5, 311197;
a(4) = 6, 3111197;
a(5) = 11, 311111111197, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [0..500] | IsPrime((28*10^n+773) div 9)]; // Vincenzo Librandi, Aug 01 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(28*10^# + 773)/9] &]
  • PARI
    is(n)=ispseudoprime((28*10^n+773)/9) \\ Charles R Greathouse IV, Jun 13 2017

A275523 Numbers k such that 2*10^k + 93 is prime.

Original entry on oeis.org

1, 2, 6, 7, 8, 11, 42, 73, 115, 131, 163, 178, 247, 320, 343, 346, 736, 1230, 1556, 3746, 5946, 6020, 6566, 6770, 11302, 14024, 29062, 33268, 37424, 42187, 49216, 51000, 79242, 81287
Offset: 1

Views

Author

Robert Price, Jul 31 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 0 followed by the digits 93 is prime (see Example section).
a(35) > 10^5.

Examples

			6 is in this sequence because 2*10^6 + 93 = 2000093 is prime.
Initial terms and associated primes:
a(1) = 1, 113;
a(2) = 2, 293;
a(3) = 6, 2000093;
a(4) = 7, 20000093;
a(5) = 8, 200000093, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[2*10^# + 93] &]
  • PARI
    is(n)=ispseudoprime(2*10^n+93) \\ Charles R Greathouse IV, Jun 13 2017

A275524 Numbers k such that (56*10^k + 223)/9 is prime.

Original entry on oeis.org

0, 2, 3, 5, 8, 32, 36, 53, 92, 126, 156, 158, 536, 639, 846, 1356, 1953, 2237, 4407, 5082, 17447, 17922, 24806, 25926, 29699, 30474, 37424, 63942
Offset: 1

Views

Author

Robert Price, Jul 31 2016

Keywords

Comments

For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 2 followed by the digits 47 is prime (see Example section).
a(29) > 10^5.

Examples

			3 is in this sequence because (56*10^3 + 223)/9 = 6247 is prime.
Initial terms and associated primes:
a(1) = 0, 31;
a(2) = 2, 647;
a(3) = 3, 6247;
a(4) = 5, 622247;
a(5) = 8, 622222247, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [0..500] | IsPrime((56*10^n+223) div 9)]; // Vincenzo Librandi, Aug 01 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[(56*10^# + 223)/9] &]
  • PARI
    is(n)=ispseudoprime((56*10^n+223)/9) \\ Charles R Greathouse IV, Jun 13 2017

A275525 Numbers k such that (73*10^k + 107)/9 is prime.

Original entry on oeis.org

2, 3, 5, 6, 11, 12, 26, 32, 36, 75, 137, 143, 279, 290, 363, 716, 770, 1377, 1638, 4470, 5952, 10526, 15132, 27054, 81485
Offset: 1

Views

Author

Robert Price, Aug 11 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 23 is prime (see Example section).
a(26) > 10^5.

Examples

			3 is in this sequence because (73*10^3+107)/9 = 8123 is prime.
Initial terms and associated primes:
a(1) = 2, 823;
a(2) = 3, 8123;
a(3) = 5, 811123;
a(4) = 6, 8111123;
a(5) = 11, 811111111123, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(73*10^#+107)/9] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((73*10^n+107)/9), print1(n, ", "))); \\ Altug Alkan, Aug 11 2016

A275538 Numbers k such that (38*10^k + 547)/9 is prime.

Original entry on oeis.org

1, 3, 4, 9, 10, 13, 19, 21, 25, 28, 70, 81, 97, 106, 291, 369, 460, 577, 4705, 5427, 7153, 7191, 7885, 12070, 20794, 34855
Offset: 1

Views

Author

Robert Price, Aug 01 2016

Keywords

Comments

For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 2 followed by the digits 83 is prime (see Example section).
a(27) > 10^5.

Examples

			3 is in this sequence because (38*10^3 + 547)/9 = 4283 is prime.
Initial terms and associated primes:
a(1) = 1, 103;
a(2) = 3, 4283;
a(3) = 4, 42283;
a(4) = 9, 4222222283;
a(5) = 10, 42222222283, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(38*10^# + 547)/9] &]
  • PARI
    isok(n) = isprime((38*10^n + 547)/9); \\ Michel Marcus, Aug 01 2016

A275802 Numbers k such that (76*10^k + 167)/9 is prime.

Original entry on oeis.org

1, 2, 4, 5, 7, 10, 16, 19, 28, 37, 41, 44, 53, 311, 490, 1252, 4360, 4732, 5575, 6833, 8878, 11171, 11396, 13079, 14903, 76615
Offset: 1

Views

Author

Robert Price, Aug 09 2016

Keywords

Comments

For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 4 followed by the digits 63 is prime (see Example section).
a(27) > 10^5.

Examples

			4 is in this sequence because (76*10^4+167)/9 = 84463 is prime.
Initial terms and associated primes:
a(1) = 1, 103;
a(2) = 2, 863;
a(3) = 4, 84463;
a(4) = 5, 844463;
a(5) = 7, 84444463, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(76*10^#+167)/9] &]
  • PARI
    is(n)=ispseudoprime((76*10^n+167)/9) \\ Charles R Greathouse IV, Jun 13 2017

A275978 Numbers k such that (101*10^k + 1)/3 is prime.

Original entry on oeis.org

1, 4, 6, 12, 34, 54, 60, 61, 73, 148, 349, 552, 649, 967, 1044, 2521, 4501, 5721, 6133, 9052, 9880, 16126, 16215, 19146, 61770
Offset: 1

Views

Author

Robert Price, Aug 15 2016

Keywords

Comments

Numbers k such that the digits 33 followed by k-1 occurrences of the digit 6 followed by the digit 7 is prime (see Example section).
a(26) > 10^5.

Examples

			4 is in this sequence because (101*10^4 + 1)/3 = 336667 is prime.
Initial terms and associated primes:
a(1) = 1, 337;
a(2) = 4, 336667;
a(3) = 6, 33666667;
a(4) = 12, 33666666666667;
a(5) = 34, 336666666666666666666666666666666667, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(101*10^# + 1)/3] &]
  • PARI
    isok(n) = isprime((101*10^n + 1)/3); \\ Michel Marcus, Aug 16 2016

A276046 Numbers k such that (26*10^k - 23)/3 is prime.

Original entry on oeis.org

1, 2, 10, 16, 78, 97, 125, 138, 192, 242, 290, 373, 408, 467, 583, 892, 899, 1709, 1944, 2154, 3618, 5225, 8974, 9377, 12504, 20042, 49106, 63073, 92152, 147973
Offset: 1

Views

Author

Robert Price, Aug 17 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 59 is prime (see Example section).
a(31) > 2*10^5.

Examples

			2 is in this sequence because (26*10^2 - 23)/3 = 859 is prime.
Initial terms and associated primes:
a(1) = 1, 79;
a(2) = 2, 859;
a(3) = 10, 86666666659;
a(4) = 16, 86666666666666659, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(26*10^# - 23)/3] &]
  • PARI
    is(n)=ispseudoprime((26*10^n - 23)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(30) from Robert Price, Dec 19 2019

A276047 Numbers k such that 4*10^k + 21 is prime.

Original entry on oeis.org

1, 2, 3, 7, 15, 22, 30, 35, 44, 73, 89, 91, 224, 533, 821, 1037, 1338, 1458, 1777, 2046, 2257, 2877, 3047, 3407, 13398, 42766, 55906, 61625, 66653, 123113, 229836, 238163
Offset: 1

Views

Author

Robert Price, Aug 17 2016

Keywords

Comments

For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 0 followed by the digits 21 is prime (see Example section).
a(33) > 3*10^5.

Examples

			3 is in this sequence because 4*10^3 + 21 = 4021 is prime.
Initial terms and associated primes:
a(1) = 1, 61;
a(2) = 2, 421;
a(3) = 3, 4021;
a(4) = 7, 40000021;
a(5) = 15, 4000000000000021, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[4*10^# + 21] &]
  • PARI
    is(n)=ispseudoprime(4*10^n + 21) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(30) from Robert Price, Dec 09 2018
a(31) - a(32) from Robert Price, Jun 01 2023
Previous Showing 91-100 of 498 results. Next

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

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