A087512 Primes consisting only of digits 1 and 4 occurring with equal frequency.

41, 14441411, 41414411, 44114141, 1144141441, 1144144411, 1144441141, 1411414441, 1441411441, 1441444111, 1444114141, 4111144441, 4111444411, 4114414141, 4141141441, 4141144141, 4144111441, 4411114441, 4411144141, 4411414411, 4414141141, 4414441111

Offset: 1

Author

Paul D. Hanna and Amarnath Murthy, Sep 11 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

• Andrew Howroyd, Table of n, a(n) for n = 1..5319 (first 5001 terms from Harvey P. Dale)

Crossrefs

Cf. A087510, A087511, A087513.

Programs

Mathematica

Union[Flatten[Table[Select[FromDigits/@Permutations[Flatten[Table[{1,4},{n}]]],PrimeQ],{n,5}]]] (* Harvey P. Dale, Nov 21 2014 *)

PARI

\\ Needs B() from A087510.
concat(vector(6,k,B(k,1,4,isprime))) \\ Andrew Howroyd, Sep 21 2024

Extensions

More terms from Harvey P. Dale, Nov 21 2014

Offset changed by Andrew Howroyd, Sep 21 2024