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

Author

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

Keywords

• nonn
• base
• nice
• easy

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.

Examples

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

Crossrefs

Cf. A038618, A048376, A057630.

Programs

Mathematica

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

PARI

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

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