A087538 Primes consisting only of digits 8 and 9 occurring with equal frequency.

89, 88989899, 98988899, 98989889, 99898889, 8889899899, 8889988999, 8889998899, 8898988999, 8898989989, 8899889989, 8988998899, 8988999889, 8989889899, 8989889989, 8989899889, 8989988899, 8998998889, 8999888899

Offset

0,1

Comments

There are 18 digit pairs which can produce such primes. (1,0),(7,0),(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).

Links

Table of n, a(n) for n=0..18.

Prog

(PARI) /* Primes consisting only of digits x and y, occurring with equal frequency. */ x=8; y=9; d1=x; d2=y; k=0; a=vector(100); for(n=1, 3000, B=binary(n); L=length(B); s=sum(j=1, length(B), B[j]); if(L%2==0 & s==L/2, C=vector(L, n, (d2-d1)*B[n]+d1); p=subst(Pol(C), x, 10); if(isprime(p), if(k<100, k++; a[k]=p)); D=vector(L, n, d2-(d2-d1)*B[n]); q=subst(Pol(D), x, 10); if(isprime(q ), if(k<100, k++; a[k]=q))); ); a=vector(k, n, a[n]); vecsort(a)

Crossrefs

Cf. A087510, A087511, A087537.

Sequence in context: A080051 A243316 A072314 * A087341 A093405 A348166

Adjacent sequences: A087535 A087536 A087537 * A087539 A087540 A087541

Keyword

base,nonn

Author

Amarnath Murthy and Paul D. Hanna, Sep 12 2003

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009

Status

approved