A057628 Primes such that replacing each digit d with d copies of the digit d produces a prime. Zeros are not allowed.

11, 31, 53, 131, 149, 223, 283, 311, 313, 331, 397, 463, 641, 691, 937, 941, 1439, 1511, 1741, 1871, 1949, 1993, 1999, 2111, 2447, 2939, 3163, 3391, 3433, 3499, 3559, 3593, 3659, 3911, 3931, 5227, 5399, 5923, 6163, 6269, 6653, 6719, 7177, 7741, 8389

Offset

1,1

Comments

"Replacing each digit d with d copies of the digit d" is the function A048376. Therefore this is the largest subset of A038618 stable under the map A048376.

Links

Table of n, a(n) for n=1..45.

Example

E.g. 641 becomes 66666644441 which is also prime.

Mathematica

Select[Prime[Range[1500]], PrimeQ[FromDigits[Flatten[Table[#, {#}]&/@ IntegerDigits[#]]]]&&DigitCount[#, 10, 0]==0&]  (* Harvey P. Dale, Mar 27 2011 *)

Prog

(PARI) is_A057628(n)={vecmin(digits(n)) && is_A057630(n)} \\ M. F. Hasler, Jan 23 2013

Crossrefs

Cf. A038618, A048376, A057630.

Sequence in context: A230329 A232764 A057630 * A144364 A226922 A031372

Adjacent sequences: A057625 A057626 A057627 * A057629 A057630 A057631

Keyword

nonn,base,nice,easy

Author

G. L. Honaker, Jr., Oct 10 2000

Extensions

More terms from Patrick De Geest, Oct 15 2000.

Offset changed to 1, according to OEIS conventions, by M. F. Hasler, Jan 23 2013

Status

approved