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A087367
Twin primes whose digits are primes.
0
3, 5, 227, 2237, 3257, 3527, 3557, 7757, 22277, 23537, 25577, 27527, 27737, 37337, 55337, 57527, 57557, 72227, 77237, 223337, 223757, 225527, 233327, 272537, 277577, 327557, 327737, 337277, 357737, 375257, 377327, 522227, 525377, 553277
OFFSET
3,1
COMMENTS
Except for 3 and 5 these numbers must end in 7. If twin primes are infinite can we prove these numbers are infinite?
PROG
(PARI) pdigitp(n) = { forprime(x=2, n, flag=1; y=x; if(isprime(x+2), for(j=1, length(Str(y)), r = y%10; if(!isprime(r), flag=0); y = floor(y/10); ); if(flag, print1(x", ")); ) ) }
CROSSREFS
Sequence in context: A224537 A175133 A012817 * A058846 A268535 A268695
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Oct 21 2003
STATUS
approved