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Search: id:A140291
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| A140291 |
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Lucky numbers whose digital reversals are also lucky numbers. |
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+0
1
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| 1, 3, 7, 9, 13, 15, 31, 37, 51, 73, 99, 111, 115, 133, 141, 151, 163, 169, 171, 189, 193, 195, 303, 327, 331, 339, 361, 385, 391, 393, 399, 511, 529, 535, 537, 579, 583, 591, 717, 723, 727, 729, 735, 739, 777, 787, 925, 927, 933, 937, 961, 975, 979, 981, 993
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Remove the palindromes (1, 3, 7, 9, 111, 141, 151, 171, 303, 393, 535, 717, 727, 777, 787, 979, ...) and we have what might be called ykcul, those lucky numbers which, when reversed, are different lucky numbers, by analogy with emirps and emirpimes (A097393). The slight interest here is whether, as lucky numbers have statistical distribution similar to primes, whether the lucky palindromes and yckul have asymptotic density the same as palprimes (A002385) and emirps (A006567).
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FORMULA
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{n such that n is in A000959 and R(n) is in A000959}.
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CROSSREFS
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Cf. A000989, A002385, A006567, A097393.
Sequence in context: A118567 A118561 A057701 this_sequence A032367 A063204 A130568
Adjacent sequences: A140288 A140289 A140290 this_sequence A140292 A140293 A140294
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KEYWORD
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base,easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), May 24 2008
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