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A068679
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Numbers which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).
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4
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1, 3, 7, 13, 31, 49, 63, 81, 91, 99, 103, 109, 117, 123, 151, 181, 193, 213, 231, 279, 319, 367, 427, 459, 571, 601, 613, 621, 697, 721, 801, 811, 951, 987, 1113, 1117, 1131, 1261, 1821, 1831, 1939, 2101, 2149, 2211, 2517, 2611, 3151, 3219, 4011, 4411, 4519, 4887, 5031, 5361, 6231, 6487, 6871, 7011, 7209, 8671, 9141, 9801, 10051
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| If R(p) = (10^p -1)/9 is a prime then {(10^(p-1) -1}/9 belongs to this sequence.
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LINKS
| C. Caldwell, Prime Pages
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EXAMPLE
| 123 belongs to this sequence as the numbers 1123, 1213, 1231 obtained by inserting a 1 in all possible ways are all primes.
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CROSSREFS
| Cf. A068673, A068674, A068677, A069246.
Sequence in context: A002383 A163418 A161218 * A006978 A060424 A119962
Adjacent sequences: A068676 A068677 A068678 * A068680 A068681 A068682
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 02 2002
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EXTENSIONS
| More terms from Eli McGowan (ejmcgowa(AT)mail.lakeheadu.ca), Apr 11 2002
More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 16 2002
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