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A104718
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Concatenations of pairs of primes that differ by 8.
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6
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311, 513, 1119, 2331, 2937, 5361, 5967, 7179, 8997, 101109, 131139, 149157, 173181, 191199, 233241, 263271, 269277, 359367, 389397, 401409, 431439, 449457, 479487, 491499, 563571, 569577, 593601, 599607, 653661, 683691, 701709, 719727, 743751
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| There are no primes in this sequence after a(1) = 311, as all values thereafter are divisible by 3. Semiprimes in this sequence include: a(3) = 1119 = 3 * 373 a(6) = 5361 = 3 * 1787, a(8) = 7179 = 3 * 2393, a(9) = 8997 = 3 * 2999, a(10) = 101109 = 3 * 33703, a(13) = 173181 = 3 * 57727, a(15) = 233241 = 3 * 77747, a(17) = 269277 = 3 * 89759, a(21) = 431439 = 3 * 143813, a(26) = 569577 = 3 * 189859, a(35) = 821829 = 3 * 273943.
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FORMULA
| a(n) = A023202(n) concatenated with A023202(n)+8.
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CROSSREFS
| Cf. A000040, A001358, A023202, A103195, A103206, A104719.
Sequence in context: A113155 A142626 A142950 * A142576 A025024 A173596
Adjacent sequences: A104715 A104716 A104717 * A104719 A104720 A104721
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KEYWORD
| base,easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 20 2005
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