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

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

1,1

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..9931

Prog

(PARI) \\ Needs B() from A087510.
concat(vector(6, k, B(k, 7, 9, isprime))) \\ Andrew Howroyd, Sep 20 2024

Crossrefs

Cf. A087510, A087511, A087536.

Sequence in context: A065211 A106757 A285228 * A117840 A296012 A193142

Adjacent sequences: A087534 A087535 A087536 * A087538 A087539 A087540

Keyword

base,nonn

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009

Offset changed and a(22) onwards from Andrew Howroyd, Sep 20 2024

Status

approved