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

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

Harvey P. Dale, Table of n, a(n) for n = 0..5000

Maple

Primes consisting only of digits x and y, occurring with equal frequency. 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)

Mathematica

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

Crossrefs

Cf. A087510, A087514, A087515.

Sequence in context: A116124 A068533 A093631 * A176272 A173418 A147667

Adjacent sequences: A087510 A087511 A087512 * A087514 A087515 A087516

Keyword

base,nonn

Author

Amarnath Murthy and Paul D. Hanna, Sep 11 2003

Status

approved