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.

Showing 1-4 of 4 results.

A111021 Integers k such that 7*10^k + 31 is a prime number.

Original entry on oeis.org

1, 8, 11, 143, 203, 2727, 2911, 3339, 17039
Offset: 1

Views

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Keywords

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "70031".
a(10) > 10^5. - Robert Price, Jan 28 2017

Examples

			k = 11 is a term because 7*10^11 + 31 = 7*100000000000 + 31 = 700000000000 + 31 = 700000000031, which is a prime.

Links

Crossrefs

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.

Programs

  • Magma
    [n: n in [1..300] | IsPrime(7*10^n+31)]; // Vincenzo Librandi, Jul 03 2016
  • Mathematica
    Select[Range[0, 10000], PrimeQ[7 10^# + 31] &] (* Vincenzo Librandi, Jul 03 2016 *)

Extensions

a(9) from Ray Chandler, Dec 23 2010
a(1) = 1 prepended by Vincenzo Librandi, Jul 03 2016

A258932 Numbers k such that 10^k + 103 is prime.

Original entry on oeis.org

1, 3, 4, 5, 7, 9, 10, 11, 27, 35, 85, 169, 209, 221, 321, 347, 603, 610, 1229, 1391, 2171, 2303, 2679, 3977, 4545, 5721, 7090, 35877
Offset: 1

Views

Author

Vincenzo Librandi, Jun 15 2015

Keywords

Comments

a(29) > 60000. - Michael S. Branicky, Apr 27 2025

Examples

			For n = 3, a(3) = 10^3 + 103 = 1103, which is prime.

Crossrefs

Sequences of the type 10^n+k: A049054 (k=3), A088274 (k=7), A088275 (k=9), A095688 (k=13), A108052 (k=19), A108050 (k=21), A108312 (k=27), A107083 (k=31), A107084 (k=33), A135109 (k=37), A135108 (k=39), A108049 (k=43), A108054 (k=49), A135118 (k=51), A135119 (k=57), A135116 (k=61), A135115 (k=63), A135113 (k=67), A135114 (k=69), A135132 (k=73), A135131 (k=79), A137848 (k=81), A135117 (k=87), A110918 (k=91), A135112 (k=93), A135107 (k=97), A110980 (k=99), this sequence (k=103), A258933 (k=109), A165508 (k=111), A248349 (k=123456789), A248351 (k=987654321).

Programs

  • Magma
    [n: n in [1..600] | IsPrime(10^n+103)];
  • Mathematica
    Select[Range[5000], PrimeQ[10^# + 103] &]
  • PARI
    is(n)=ispseudoprime(10^n+103) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(26)-a(28) from Jens Kruse Andersen, Jun 23 2015

A111022 Integers n such that 8*10^n+21 is prime.

Original entry on oeis.org

0, 1, 2, 4, 10, 40, 55, 162, 264, 506, 870, 948, 1339, 3587, 6428, 48490, 81487
Offset: 1

Views

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Keywords

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "80021".
a(18) > 10^5. - Robert Price, Feb 06 2017

Examples

			n = 4 is a member because: 8*10^4+21 = 8*10000+21 = 80000+21 = 80021, which is prime.

Links

Crossrefs

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.

Extensions

a(15) from Ray Chandler, Dec 23 2010
Prepended a(1)=0 and a(2)=1 by Robert Price, Feb 06 2017
a(16)-a(17) from Robert Price, Feb 06 2017

A111023 Integers n such that 9*10^n + 11 is a prime number.

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 16, 20, 27, 115, 180, 274, 576, 1111, 2404, 5127, 8082, 9514, 12808, 14752, 15926, 22670, 37432, 41988, 53707, 72595, 92742
Offset: 1

Views

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Keywords

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "90w11".
a(28) > 10^5. - Robert Price, Jan 28 2017

Examples

			n = 6 is a member because 9*10^6 + 11 = 9*1000000 + 11 = 9000011, which is prime.

Links

Crossrefs

Cf. A100275 = numbers n such that 9*10^n-11 is prime.
Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.

Programs

  • Mathematica
    Do[If[PrimeQ[9*10^n+11],Print[n]],{n,1,1300}] (* Zak Seidov, Sep 14 2006 *)

Extensions

Edited by N. J. A. Sloane, Apr 11 2008
a(16)-a(22) from Ray Chandler, Dec 23 2010
a(23)-a(27) from Robert Price, Jan 28 2017
Showing 1-4 of 4 results.

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

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