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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A271340 Numbers k such that (14*10^k + 73)/3 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 7, 10, 15, 19, 32, 54, 68, 114, 148, 227, 238, 286, 405, 789, 857, 1310, 2314, 3613, 4103, 4215, 5135, 6094, 8023, 8718, 16899, 34215, 41989, 81585, 85010, 143097, 165282, 199447
Offset: 1

Views

Author

Robert Price, Apr 05 2016

Keywords

Comments

For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 6 followed by the digits 91 is prime (see Example section).
a(39) > 2*10^5.

Examples

			3 is in this sequence because (14*10^3 + 73)/3 = 4691 is prime.
Initial terms and associated primes:
a(1) = 0, 29;
a(2) = 1, 71;
a(3) = 2, 491;
a(4) = 3, 4691;
a(5) = 4, 46691;
a(6) = 6, 4666691, etc.

Links

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271109, A271269.

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(14*10^# + 73)/3] &]
  • PARI
    is(n)=ispseudoprime((14*10^n + 73)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(36)-a(38) from Robert Price, Dec 26 2018

A271360 Numbers k such that 5*10^k + 87 is prime.

Original entry on oeis.org

1, 2, 3, 4, 6, 16, 38, 39, 46, 61, 62, 100, 116, 152, 190, 298, 472, 642, 688, 1676, 1971, 2338, 4389, 4520, 4986, 7765, 9428, 10820, 18984, 19797, 35360, 42146, 168807
Offset: 1

Views

Author

Robert Price, Apr 05 2016

Keywords

Comments

For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 0 followed by the digits 87 is prime (see Example section).
a(34) > 2*10^5.

Examples

			3 is in this sequence because 5*10^3 + 87 = 5087 is prime.
Initial terms and associated primes:
a(1) = 1, 137;
a(2) = 2, 587;
a(3) = 3, 5087;
a(4) = 4, 50087;
a(5) = 6, 5000087, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[5*10^# + 87] &]
  • PARI
    is(n)=ispseudoprime(5*10^n + 87) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(33) from Robert Price, Feb 24 2019

A271361 Numbers k such that 63*10^k + 1 is prime.

Original entry on oeis.org

1, 2, 12, 21, 27, 30, 33, 44, 46, 76, 78, 83, 84, 92, 582, 750, 787, 3218, 3290, 5617, 6385, 13960, 22705, 27636, 36497, 50349, 51169, 70381, 70486, 73096
Offset: 1

Views

Author

Robert Price, Apr 05 2016

Keywords

Comments

Numbers k such that the digits 63 followed by k-1 occurrences of the digit 0 followed by the digit 1 is prime (see Example section).
a(31) > 10^5.

Examples

			2 is in this sequence because 63*10^2+1 = 6301 is prime.
Initial terms and associated primes:
a(1) = 1, 631;
a(2) = 2, 6301;
a(3) = 12, 63000000000001;
a(4) = 21, 63000000000000000000001;
a(5) = 27, 63000000000000000000000000001, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[63*10^#+1] &]
  • PARI
    is(n)=ispseudoprime(63*10^n+1) \\ Charles R Greathouse IV, Jun 13 2017

A271375 Numbers k such that (38*10^k + 637)/9 is prime.

Original entry on oeis.org

1, 4, 14, 19, 25, 26, 32, 41, 59, 79, 83, 101, 103, 200, 308, 314, 548, 565, 620, 922, 1102, 1960, 2245, 2254, 5393, 5935, 6227, 14350, 25070
Offset: 1

Views

Author

Robert Price, Apr 05 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 93 is prime (see Example section).
a(30) > 2*10^5.

Examples

			4 is in this sequence because (38*10^4+637)/9 = 42293 is prime.
Initial terms and associated primes:
a(1) = 1, 113;
a(2) = 4, 42293;
a(3) = 14, 422222222222293;
a(4) = 19, 42222222222222222293;
a(5) = 25, 42222222222222222222222293, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(38*10^# + 637)/9] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((38*10^n + 637)/9), print1(n, ", "))); \\ Altug Alkan, Apr 05 2016

A271377 Numbers k such that (28*10^k - 43)/3 is prime.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 13, 43, 112, 114, 127, 242, 247, 251, 335, 450, 616, 816, 1237, 1448, 4303, 4865, 5414, 6427, 9045, 10391, 12651, 25071, 27901, 50362, 58843, 67378, 68107, 262655
Offset: 1

Views

Author

Robert Price, Apr 05 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 19 is prime (see Example section).
a(36) > 3*10^5.

Examples

			3 is in this sequence because (28*10^3 - 43)/3 = 9319 is prime.
Initial terms and associated primes:
a(1) = 1, 79;
a(2) = 2, 919;
a(3) = 3, 9319;
a(4) = 4, 93319;
a(5) = 5, 933319, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(28*10^# - 43)/3] &]
  • PARI
    lista(nn) = for(n=1, nn, if(ispseudoprime((28*10^n - 43)/3), print1(n, ", "))); \\ Altug Alkan, Apr 05 2016

Extensions

a(35) from Robert Price, Jul 02 2023

A271505 Numbers k such that (82*10^k + 161)/9 is prime.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 14, 17, 22, 49, 130, 136, 142, 170, 196, 220, 967, 1816, 2165, 2542, 2635, 3979, 10319, 11096, 12191, 14381, 14444, 17558, 18230, 42176, 113681
Offset: 1

Views

Author

Robert Price, Apr 08 2016

Keywords

Comments

For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 1 followed by the digits 29 is prime (see Example section).
a(32) > 2*10^5.

Examples

			4 is in this sequence because (82*10^4+161)/9 = 91129 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 2, 929;
a(3) = 4, 91129;
a(4) = 5, 911129;
a(5) = 7, 91111129, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(82*10^# + 161)/9] &]
  • PARI
    is(n)=ispseudoprime((82*10^n + 161)/9) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(31) from Robert Price, Oct 31 2019

A271506 Numbers k such that (7*10^k + 179)/3 is prime.

Original entry on oeis.org

1, 2, 3, 7, 8, 36, 41, 46, 74, 76, 88, 103, 115, 188, 194, 257, 310, 399, 511, 515, 776, 1134, 1404, 6545, 6569, 17600, 22209, 24397, 24842, 46957, 116684, 118607, 131339, 202267
Offset: 1

Views

Author

Robert Price, Apr 08 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 3 followed by the digits 93 is prime (see Example section).
a(35) > 3*10^5.

Examples

			3 is in this sequence because (7*10^3 + 179)/3 = 2393 is prime.
Initial terms and associated primes:
a(1) = 1, 83;
a(2) = 2, 293;
a(3) = 3, 2393;
a(4) = 7, 23333393;
a(5) = 8, 233333393. etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(7*10^# + 179)/3] &]
Join[{1},Flatten[Position[Table[100*FromDigits[PadRight[{2},n,3]]+93,{n,47000}],?PrimeQ]]+1] (* _Harvey P. Dale, Dec 11 2018 *)
  • PARI
    is(n)=ispseudoprime((7*10^n+179)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(31)-a(33) from Robert Price, Sep 01 2018
a(34) from Robert Price, Jun 21 2023

A271548 Numbers k such that 4*10^k + 19 is prime.

Original entry on oeis.org

0, 1, 2, 3, 9, 11, 19, 27, 31, 36, 42, 69, 86, 98, 152, 205, 533, 587, 1302, 1506, 1521, 1573, 1807, 3906, 6461, 9081, 11766, 12595, 15697, 17154, 30507, 36074, 52667, 61367, 122377, 169759
Offset: 1

Views

Author

Robert Price, Apr 09 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 19 is prime (see Example section).
a(37) > 3*10^5.

Examples

			3 is in this sequence because 4*10^3 + 19 = 4019 is prime.
Initial terms and associated primes:
a(1) = 0, 23;
a(2) = 1, 59;
a(3) = 2, 419;
a(4) = 3, 4019;
a(5) = 9, 4000000019, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[4*10^# + 19] &]
  • PARI
    is(n)=ispseudoprime(4*10^n + 19) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(35)-a(36) from Robert Price, Oct 22 2018

A271585 Numbers k such that (7*10^k + 143)/3 is prime.

Original entry on oeis.org

1, 2, 3, 6, 7, 10, 11, 25, 26, 32, 122, 123, 126, 161, 292, 320, 743, 1630, 2738, 3178, 4814, 4833, 5030, 7035, 8151, 12554, 13954, 15113, 80490, 96112, 121487, 190683
Offset: 1

Views

Author

Robert Price, Apr 10 2016

Keywords

Comments

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 3 followed by the digits 81 is prime (see Example section).
a(33) > 2*10^5.

Examples

			3 is in this sequence because (7*10^3 + 143)/3 = 2381 is prime.
Initial terms and associated primes:
a(1) = 1, 71;
a(2) = 2, 281;
a(3) = 3, 2381;
a(4) = 6, 2333381;
a(5) = 7, 23333381, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[(7*10^# + 143)/3] &]
  • PARI
    is(n)=ispseudoprime((7*10^n+143)/3) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(31)-a(32) from Robert Price, Mar 30 2018

A271618 Numbers k such that 10^k - 801 is prime.

Original entry on oeis.org

3, 4, 6, 14, 15, 16, 20, 46, 52, 114, 165, 468, 504, 568, 713, 748, 899, 958, 992, 1043, 1348, 2388, 3182, 4102, 8847, 10899, 11908, 18852, 25214, 40151, 40290, 51207, 71910, 166324
Offset: 1

Views

Author

Robert Price, Apr 11 2016

Keywords

Comments

For k > 2, numbers k such that k-3 occurrences of the digit 9 followed by the digits 199 is prime (see Example section).
a(35) > 2*10^5.

Examples

			6 is in this sequence because 10^6-801 = 999199 is prime.
Initial terms and associated primes:
a(1) = 3, 199;
a(2) = 4, 9199;
a(3) = 6, 999199;
a(4) = 14, 99999999999199;
a(5) = 15, 999999999999199, etc.

Links

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 100000], PrimeQ[10^#-801] &]
  • PARI
    is(n)=ispseudoprime(10^n-801) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(34) from Robert Price, Feb 14 2018
Previous Showing 31-40 of 497 results. Next

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

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