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

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

Offset

1,1

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..5353

Mathematica

Sort[Flatten[Table[Select[FromDigits/@Permutations[Flatten[Table[{5, 9}, {n}]]], PrimeQ], {n, 5}]]] (* Harvey P. Dale, May 31 2013 *)

Prog

(PARI) \\ Needs B() from A087510.
concat(vector(6, k, B(k, 5, 9, isprime))) \\ Andrew Howroyd, Sep 20 2024

Crossrefs

Cf. A087510, A087511, A087534.

Sequence in context: A178066 A191947 A093403 * A058931 A092914 A022083

Adjacent sequences: A087532 A087533 A087534 * A087536 A087537 A087538

Keyword

base,nonn

Author

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

Extensions

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

Status

approved