A087367 Twin primes whose digits are primes.

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?

Links

Table of n, a(n) for n=3..36.

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

Adjacent sequences: A087364 A087365 A087366 * A087368 A087369 A087370

Keyword

easy,nonn,base

Author

Cino Hilliard, Oct 21 2003

Status

approved