A087513 Primes consisting only of digits 1 and 6 occurring with equal frequency.

61, 16166611, 16616161, 61116661, 61661161, 66161611, 1166116661, 1166166161, 1166166611, 1166616161, 1616616611, 1661116661, 6111166661, 6111666611, 6116116661, 6161161661, 6161166161, 6161166611, 6161661161, 6166111661, 6166161161, 6611616611, 6616161161, 6616161611

Offset: 1

Author

Amarnath Murthy and Paul D. Hanna, 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..5201 (first 5001 terms from Harvey P. Dale)

Crossrefs

Cf. A087510, A087511, A087512.

Programs

Mathematica

Table[Select[FromDigits/@Permutations[PadRight[{},2*n,{1,6}]],PrimeQ],{n,5}]//Flatten//Sort (* Harvey P. Dale, May 28 2019 *)

PARI

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

Extensions

Offset changed by Andrew Howroyd, Sep 21 2024