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.

Previous Showing 11-19 of 19 results.

A087532 Primes consisting only of digits 3 and 8 occurring with equal frequency.

Original entry on oeis.org

83, 38383883, 88838333, 3338388883, 3388338883, 3388833883, 3388838833, 3833388883, 3838383883, 3838388383, 3838838383, 3838883383, 3883883833, 8333888383, 8338383883, 8338888333, 8383338883, 8383388383, 8383888333, 8388338383, 8388883333, 8833383883
Offset: 1

Views

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087531.

Programs

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Offset changed and a(20) onwards from Andrew Howroyd, Sep 20 2024

A087533 Primes consisting only of digits 4 and 7 occurring with equal frequency.

Original entry on oeis.org

47, 47447747, 77474447, 4447747747, 4744477747, 4744747477, 4744747747, 4747444777, 4747747447, 4774744477, 4774747447, 7444477477, 7447474477, 7744744747, 7744747447, 7747444477, 7747447447, 7747744447, 44444477777477, 44447447774777, 44447474777477
Offset: 1

Views

Author

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087532.

Programs

  • Mathematica
    Table[Select[FromDigits/@Permutations[PadRight[{},2n,{4,7}]],PrimeQ],{n,7}]//Flatten//Sort (* Harvey P. Dale, May 05 2016 *)
  • PARI
    \\ Needs B() from A087510.
concat(vector(6,k,B(k,4,7,isprime))) \\ Andrew Howroyd, Sep 20 2024

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Corrected by Harvey P. Dale, May 05 2016
Offset changed by Andrew Howroyd, Sep 20 2024

A087534 Primes consisting only of digits 4 and 9 occurring with equal frequency.

Original entry on oeis.org

44994949, 49444999, 49494499, 49499449, 94449499, 4449449999, 4449494999, 4494494999, 4494499949, 4494949499, 4494994499, 4499449949, 4499494949, 4499944949, 4944499949, 4949444999, 4994449949, 9444499949, 9444994499, 9449494499, 9449494949, 9499444499, 9944944949
Offset: 1

Views

Author

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087533.

Programs

  • Mathematica
    Sort[Flatten[Table[Select[FromDigits/@Permutations[PadRight[{},2n,{4,9}]],PrimeQ],{n,5}]]] (* Harvey P. Dale, Aug 21 2016 *)
  • PARI
    \\ Needs B() from A087510.
concat(vector(6,k,B(k,4,9,isprime)))

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Offset changed by Andrew Howroyd, Sep 20 2024

A087535 Primes consisting only of digits 5 and 9 occurring with equal frequency.

Original entry on oeis.org

59, 55599959, 99555959, 5555995999, 5559999559, 5595959959, 5595999559, 5599595959, 5599959559, 5955559999, 5955599959, 5959559959, 5959599559, 5995559599, 5995559959, 5995995559, 5999555959, 9555599959, 9555959599, 9555995959, 9555999559, 9559595599
Offset: 1

Views

Author

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087534.

Programs

  • Mathematica
    Sort[Flatten[Table[Select[FromDigits/@Permutations[Flatten[Table[{5,9},{n}]]],PrimeQ],{n,5}]]] (* Harvey P. Dale, May 31 2013 *)
  • PARI
    \\ Needs B() from A087510.
concat(vector(6,k,B(k,5,9,isprime))) \\ Andrew Howroyd, Sep 20 2024

Extensions

Offset changed and a(20) onwards from Andrew Howroyd, Sep 20 2024

A087536 Primes consisting only of digits 6 and 7 occurring with equal frequency.

Original entry on oeis.org

67, 67766767, 76767667, 6666767777, 6667677677, 6667776767, 6667777667, 6676766777, 6676767677, 6676776677, 6677666777, 6677667767, 6677676767, 6766677767, 6766776677, 6767667677, 6767677667, 6776766677, 6776766767, 6776767667, 6777667667, 7666677677, 7666767677, 7667676677
Offset: 1

Views

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087535.

Programs

  • Mathematica
    Sort[Flatten[Table[Select[FromDigits/@Permutations[PadRight[{},2n,{6,7}]],PrimeQ],{n,5}]]] (* Harvey P. Dale, Dec 03 2012 *)
  • PARI
    \\ Needs B() from A087510.
concat(vector(6,k,B(k,6,7,isprime))) \\ Andrew Howroyd, Sep 20 2024

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Offset changed by Andrew Howroyd, Sep 20 2024

A087537 Primes consisting only of digits 7 and 9 occurring with equal frequency.

Original entry on oeis.org

79, 97, 77997979, 79779979, 79797997, 79997977, 99977797, 99979777, 7777997999, 7779799799, 7779799997, 7779979979, 7797799979, 7797979799, 7799797799, 7977799799, 7979799977, 7979979779, 7979979797, 7979979977, 7979997797, 7997799977, 7997979779, 7997997977
Offset: 1

Views

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087536.

Programs

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Offset changed and a(22) onwards from Andrew Howroyd, Sep 20 2024

A087538 Primes consisting only of digits 8 and 9 occurring with equal frequency.

Original entry on oeis.org

89, 88989899, 98988899, 98989889, 99898889, 8889899899, 8889988999, 8889998899, 8898988999, 8898989989, 8899889989, 8988998899, 8988999889, 8989889899, 8989889989, 8989899889, 8989988899, 8998998889, 8999888899, 9888899899, 9888989899, 9889898899, 9889988989
Offset: 1

Views

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Keywords

Comments

There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

Links

Crossrefs

Cf. A087510, A087511, A087537.

Programs

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Offset changed and a(20) onwards from Andrew Howroyd, Sep 20 2024

A199306 Palindromic primes in the sense of A007500 with digits '0', '1' and '6' only.

Original entry on oeis.org

11, 101, 1061, 1601, 10061, 10601, 11161, 16001, 16061, 16111, 16661, 101611, 106661, 116101, 166601, 1011601, 1016011, 1016611, 1061101, 1066111, 1106101, 1110611, 1111661, 1116601, 1160111, 1160611, 1166101, 1600061, 1611161, 1616161, 1660661, 1661111, 10011101, 10100161, 10106111
Offset: 1

Views

Author

M. F. Hasler, Nov 06 2011

Keywords

Comments

All terms start and end with the digit '1'. This fact is used in the given PARI program.

Crossrefs

Cf. A020449 - A020472, A062350, A087510 - A087515, A199325 - A199329.

Programs

  • Magma
    [p: p in PrimesUpTo(10^8) | Set(Intseq(p)) subset [0,1,6] and IsPrime(Seqint(Reverse(Intseq(p))))]; // Bruno Berselli, Nov 07 2011
  • PARI
    a(n=50,list=0,L=[0,1,6])={ for(d=1,1e9, my(t,u=vector(d-1,i,10^(d-i))~,o=10^d+1);forvec(v=vector(#u,i,[1,#L]),isprime(t=o+vector(#u,i,L[v[i]])*u) || next; isprime(A004086(t)) || next; list & print1(t", "); n-- || return(t)))}  \\ M. F. Hasler, Nov 07 2011

A199305 Palindromic primes in the sense of A007500 with digits '0', '1' and '5' only.

Original entry on oeis.org

5, 11, 101, 151, 1151, 1511, 10151, 10501, 11551, 15101, 15511, 15551, 100511, 110051, 115001, 150011, 150151, 151051, 1001551, 1051051, 1055501, 1115551, 1150151, 1150511, 1501501, 1510511, 1550551, 1551001, 1551551, 1555111, 10000511, 10011101, 10011511, 10055011, 10101551
Offset: 1

Views

Author

M. F. Hasler, Nov 06 2011

Keywords

Comments

All terms, except for the initial 5, start and end with the digit '1'. This fact could be used to significantly speed up the given program.

Crossrefs

Cf. A020449-A020472, A199325-A199329, A087510-A087515.

Programs

  • Magma
    [p: p in PrimesUpTo(10^8) | Set(Intseq(p)) subset [0,1,5] and IsPrime(Seqint(Reverse(Intseq(p))))]; // Bruno Berselli, Nov 07 2011
  • PARI
    a(n=50, list=0, L=[0, 1, 5], needpal=1)={ for(d=1, 1e9, u=vector(d, i, 10^(d-i))~; forvec(v=vector(d, i, [1+(i==1&!L[1]), #L]), isprime(t=vector(d, i, L[v[i]])*u) || next; needpal & !isprime(A004086(t)) & next; list & print1(t", "); n-- || return(t)))}  \\ M. F. Hasler, Nov 06 2011
Previous Showing 11-19 of 19 results.

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

Content is available under The OEIS End-User License Agreement.