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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A274914 Numbers k such that 88*10^k + 7 is prime.

Original entry on oeis.org

1, 2, 3, 4, 8, 14, 17, 19, 24, 26, 30, 43, 81, 85, 171, 267, 282, 2384, 4201, 4450, 6995, 7170, 15049, 15681, 50547, 67691, 109022
Offset: 1

Views

Author

Robert Price, Nov 11 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 7 is prime (see Example section).
a(28) > 2*10^5.

Examples

			4 is in this sequence because 88*10^4 + 7 = 880007is prime.
Initial terms and associated primes:
a(1) = 1, 887;
a(2) = 2, 8807;
a(3) = 3, 88007;
a(4) = 4, 880007;
a(5) = 8, 8800000007, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[88*10^# + 7] &]
  • PARI
    is(n)=ispseudoprime(88*10^n + 7) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(27) from Robert Price, Mar 17 2020

A274976 Numbers k such that (26*10^k + 31)/3 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 7, 9, 57, 98, 122, 123, 249, 304, 318, 339, 374, 390, 476, 619, 1358, 1724, 3351, 5046, 5572, 6685, 9421, 14362, 97353
Offset: 1

Views

Author

Robert Price, Jul 14 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 77 is prime (see Example section).
a(29) > 10^5.

Examples

			3 is in this sequence because (26*10^3 + 31)/3 = 877 is prime.
Initial terms and associated primes:
a(1) = 0, 19;
a(2) = 1, 97;
a(3) = 2, 877;
a(4) = 3, 8677;
a(5) = 4, 86677, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(26*10^# + 31)/3] &]
  • PARI
    is(n)=ispseudoprime((26*10^n+31)/3) \\ Charles R Greathouse IV, Jun 13 2017

A275020 Numbers k such that (5*10^k + 91) / 3 is prime.

Original entry on oeis.org

1, 2, 3, 10, 19, 35, 43, 80, 107, 143, 199, 218, 255, 304, 353, 560, 904, 996, 1051, 6141, 8075, 9913, 11151, 28469, 75244, 108960, 122592, 178206, 187471, 257431
Offset: 1

Views

Author

Robert Price, Nov 12 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 97 is prime (see Example section).
a(31) > 3*10^5.

Examples

			3 is in this sequence because (5*10^3 + 91) / 3 = 1697 is prime.
Initial terms and associated primes:
a(1) = 1, 47;
a(2) = 2, 197;
a(3) = 3, 1697;
a(4) = 10, 16666666697;
a(5) = 19, 16666666666666666697, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(5*10^# + 91) / 3] &]
  • PARI
    is(n)=ispseudoprime((5*10^n + 91)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(26)-a(29) from Robert Price, Apr 28 2018
a(30) from Robert Price, Oct 25 2023

A275067 Numbers k such that 7*10^k + 39 is prime.

Original entry on oeis.org

1, 2, 3, 4, 12, 19, 26, 32, 84, 164, 199, 251, 306, 510, 641, 1028, 1147, 1802, 1948, 2058, 2243, 2257, 4282, 7900, 7941, 10179, 10723, 13570, 20565, 29132, 34947, 63493, 87319, 107870, 183511, 183596, 209161, 227178, 273983, 287854
Offset: 1

Views

Author

Robert Price, Jul 15 2016

Keywords

Comments

For k > 1, numbers k such that the digit 7 followed by k-2 occurrences of the digit 0 followed by the digits 39 is prime (see Example section).
a(41) > 3*10^5.

Examples

			3 is in this sequence because 7*10^3 + 39 = 7039 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 2, 739;
a(3) = 3, 7039;
a(4) = 4, 70000039;
a(5) = 12, 7000000000039, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[7*10^# + 39] &]
  • PARI
    is(n)=ispseudoprime(7*10^n+39) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(34)-a(40) from Robert Price, Jul 02 2023

A275096 Numbers k such that 2*10^k + 89 is prime.

Original entry on oeis.org

1, 3, 4, 8, 9, 10, 13, 20, 27, 74, 89, 93, 137, 139, 296, 310, 662, 749, 1249, 2540, 2848, 3309, 8677, 11573, 15286, 17125, 39526, 42187, 44476, 47823, 92897
Offset: 1

Views

Author

Robert Price, Jul 16 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 89 is prime (see Example section).
a(32) > 10^5.

Examples

			3 is in this sequence because 2*10^3 + 89 = 2089 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 3, 2089;
a(3) = 4, 20089;
a(4) = 8, 200000089;
a(5) = 9, 2000000089, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [1..500] | IsPrime(2*10^n+89)]; // Vincenzo Librandi, Jul 17 2016
  • Mathematica
    Select[Range[0, 100000], PrimeQ[2*10^# + 89] &]
  • PARI
    is(n)=ispseudoprime(2*10^n+89) \\ Charles R Greathouse IV, Jun 13 2017

A275236 Numbers k such that (28*10^k - 97)/3 is prime.

Original entry on oeis.org

1, 5, 8, 20, 27, 56, 74, 81, 107, 217, 294, 326, 525, 645, 667, 764, 863, 1885, 1961, 2913, 3056, 3192, 3327, 5480, 8455, 22797, 50147, 89141, 96265
Offset: 1

Views

Author

Robert Price, Jul 20 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 01 is prime (see Example section).
a(30) > 10^5.

Examples

			5 is in this sequence because (28*10^5-97)/3 = 877 is prime.
Initial terms and associated primes:
a(1) = 1, 61;
a(2) = 5, 933301;
a(3) = 8, 933333301;
a(4) = 20, 933333333333333333301;
a(5) = 27, 9333333333333333333333333301, etc.

Links

Crossrefs

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

Programs

  • Magma
    [n: n in [1..500] | IsPrime((28*10^n-97) div 3)]; // Vincenzo Librandi, Jul 21 2016
  • Mathematica
    Select[Range[0, 100], PrimeQ[(28*10^#-97)/3 && # > 0] &] (* Corrected by Georg Fischer, Jul 22 2019 *)
  • PARI
    is(n)=ispseudoprime((28*10^n-97)/3) \\ Charles R Greathouse IV, Jul 21 2016

A275284 Numbers k such that (29*10^k - 41)/3 is prime.

Original entry on oeis.org

1, 2, 5, 7, 13, 16, 55, 61, 65, 98, 134, 296, 354, 527, 901, 1206, 1916, 2899, 3725, 4709, 7529, 8942, 12050, 12880, 15516, 25976, 62030, 111020, 195648, 197941
Offset: 1

Views

Author

Robert Price, Jul 21 2016

Keywords

Comments

For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 6 followed by the digits 53 is prime (see Example section).
a(31) > 2*10^5.

Examples

			5 is in this sequence because (29*10^5 - 41)/3 = 966653 is prime.
Initial terms and associated primes:
a(1) = 1, 83;
a(2) = 2, 953;
a(3) = 5, 966653;
a(4) = 7, 96666653;
a(5) = 13, 96666666666653, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(29*10^# - 41)/3] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((29*10^n-41)/3), print1(n, ", "))); \\ Altug Alkan, Jul 21 2016

Extensions

a(28)-a(30) from Tyler Busby, Mar 20 2024

A275285 Numbers k such that 33*10^k + 7 is prime.

Original entry on oeis.org

1, 2, 5, 6, 30, 58, 66, 127, 138, 179, 287, 520, 767, 954, 966, 1254, 1313, 1976, 2266, 2496, 3137, 4058, 4411, 7009, 11736, 12155, 21328, 31124, 31589, 38581, 42683, 54634, 56634, 85297
Offset: 1

Views

Author

Robert Price, Jul 21 2016

Keywords

Comments

For k > 0, numbers k such that the digits 33 followed by k-1 occurrences of the digit 0 followed by the digit 7 is prime (see Example section).
a(35) > 10^5.

Examples

			5 is in this sequence because 33*10^5 + 7 = 3300007 is prime.
Initial terms and associated primes:
a(1) = 1, 337;
a(2) = 2, 3307;
a(3) = 5, 3300007;
a(4) = 6, 33000007;
a(5) = 30, 33000000000000000000000000000007, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[33*10^# + 7] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime(33*10^n+7), print1(n, ", "))); \\ Altug Alkan, Jul 21 2016

A275287 Numbers k such that (26*10^k - 107)/9 is prime.

Original entry on oeis.org

1, 2, 5, 7, 13, 23, 25, 44, 110, 157, 751, 853, 964, 1135, 2588, 2602, 2807, 2888, 3272, 4046, 4798, 16720, 21410, 22285, 25888, 34586, 51764
Offset: 1

Views

Author

Robert Price, Jul 21 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 8 followed by the digits 77 is prime (see Example section).
a(28) > 10^5.

Examples

			5 is in this sequence because (26*10^5 - 107)/9 = 288877 is prime.
Initial terms and associated primes:
a(1) = 1, 17;
a(2) = 2, 277;
a(3) = 5, 288877;
a(4) = 7, 28888877;
a(5) = 13, 28888888888877, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(26*10^# - 107)/9] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((26*10^n-107)/9), print1(n, ", "))); \\ Altug Alkan, Jul 22 2016

A275323 Numbers k such that (19*10^k + 161)/9 is prime.

Original entry on oeis.org

2, 3, 5, 6, 8, 18, 36, 59, 80, 162, 197, 200, 405, 432, 930, 1065, 1496, 1716, 3213, 5712, 6303, 7466, 14150, 23685, 54608, 59766
Offset: 1

Views

Author

Robert Price, Jul 23 2016

Keywords

Comments

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

Examples

			5 is in this sequence because (19*10^5 + 161)/9 = 211129 is prime.
Initial terms and associated primes:
a(1) = 2, 229;
a(2) = 3, 2129;
a(3) = 5, 211129;
a(4) = 6, 2111129;
a(5) = 8, 211111129, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(19*10^# + 161)/9] &]
  • PARI
    is(n)=ispseudoprime((19*10^n+161)/9) \\ Charles R Greathouse IV, Jun 13 2017
Previous Showing 81-90 of 498 results. Next

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

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