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A087535
Primes consisting only of digits 5 and 9 occurring with equal frequency.
4
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
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
KEYWORD
base,nonn
AUTHOR
EXTENSIONS
Offset changed and a(20) onwards from Andrew Howroyd, Sep 20 2024
STATUS
approved