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A087532 Primes consisting only of digits 3 and 8 occurring with equal frequency. 2
83, 38383883, 88838333, 3338388883, 3388338883, 3388833883, 3388838833, 3833388883, 3838383883, 3838388383, 3838838383, 3838883383, 3883883833, 8333888383, 8338383883, 8338888333, 8383338883, 8383388383, 8383888333 (list; graph; refs; listen; history; text; internal format)
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
PROG
(PARI) /* Primes consisting only of digits x and y, occurring with equal frequency. */ x=3; y=8; 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
Sequence in context: A201727 A116263 A287686 * A116307 A093676 A221416
KEYWORD
base,nonn
AUTHOR
EXTENSIONS
Edited by Charles R Greathouse IV, Oct 28 2009
STATUS
approved

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Last modified May 21 17:21 EDT 2024. Contains 372738 sequences. (Running on oeis4.)