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

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

Author

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

Keywords

• base
• nonn

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

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

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