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A087529 Primes consisting only of digits 4 and 3 occurring with equal frequency. 3
43, 34434343, 44334343, 44343433, 3334344443, 3343443443, 3344334443, 3344344343, 3344434433, 3433434443, 3433444433, 3434444333, 3443343443, 3444334343, 4334433443, 4334443433, 4343444333, 4344333443, 4344433343 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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 = 1..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

Select[FromDigits/@Flatten[Permutations/@Table[PadRight[{}, 2n, {4, 3}], {n, 5}], 1], PrimeQ]//Sort (* Harvey P. Dale, Aug 08 2017 *)

CROSSREFS

Cf. A087510, A087511, A087528.

Sequence in context: A125828 A177417 A116139 * A050525 A138086 A023933

Adjacent sequences:  A087526 A087527 A087528 * A087530 A087531 A087532

KEYWORD

base,nonn

AUTHOR

Paul D. Hanna and Amarnath Murthy, Sep 12 2003

STATUS

approved

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Last modified May 11 21:35 EDT 2021. Contains 343808 sequences. (Running on oeis4.)