A036946 Smallest n-digit prime containing only the digits 5 and 7, or 0 if no such prime exists.

5, 0, 557, 5557, 57557, 555557, 5555777, 55555777, 555557557, 5555555557, 55555555777, 555555575557, 5555555757757, 55555555575757, 555555555555557, 5555555555557577, 55555555555777777, 555555555557557757, 5555555555555557577, 55555555555575755777

Offset

1,1

Links

Jinyuan Wang, Table of n, a(n) for n = 1..500

Mathematica

Flatten[Join[{5, 0}, Table[Select[FromDigits/@(Join[#, {7}]&/@Tuples[ {5, 7}, n]), PrimeQ, 1], {n, 2, 20}]]] (* Harvey P. Dale, Mar 08 2013 *)

Crossrefs

Cf. A020467, A036229, A036320.

Sequence in context: A222327 A286483 A264884 * A027641 A164555 A176327

Adjacent sequences: A036943 A036944 A036945 * A036947 A036948 A036949

Keyword

nonn,base

Author

Patrick De Geest, Jan 04 1999

Extensions

More terms from Harvey P. Dale, Mar 08 2013

Status

approved