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A057630
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Primes such that replacing each digit d with d copies of the digit d produces a prime. Zeros are allowed.
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1
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11, 31, 53, 101, 131, 149, 223, 283, 311, 313, 331, 397, 463, 503, 641, 691, 937, 941, 1031, 1049, 1069, 1301, 1409, 1439, 1511, 1609, 1741, 1871, 1949, 1993, 1999, 2083, 2111, 2203, 2447, 2803, 2939, 3001, 3011, 3061, 3163, 3301, 3391, 3433, 3499, 3559
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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EXAMPLE
| E.g. 641 becomes 66666644441 which is also prime.
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MATHEMATICA
| Select[Prime[Range[500]], PrimeQ[FromDigits[Flatten[Table[#, {#}]&/@IntegerDigits[#]]]]&] [From Harvey P. Dale, Dec. 18, 2010]
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CROSSREFS
| Cf. A057628.
Sequence in context: A043904 A152293 A031287 * A057628 A144364 A031372
Adjacent sequences: A057627 A057628 A057629 * A057631 A057632 A057633
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KEYWORD
| nonn,base,nice,easy
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AUTHOR
| G. L. Honaker, Jr. (honak3r(AT)gmail.com), Oct 10 2000
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EXTENSIONS
| More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), Oct 15 2000.
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