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A176589
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Numbers n such that both concatenation of divisors of n and reverse concatenation of divisors of n are noncomposites.
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1
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1, 3, 7, 13, 31, 97, 103, 109, 151, 181, 193, 367, 409, 439, 487, 523, 571, 601, 613, 733, 811, 823, 1069, 1117, 1279, 1483, 1489, 1579, 1597, 1789, 1831, 1867, 1897, 1939, 2161, 2203, 2239, 2251, 2269, 2281, 2437, 2503, 2509, 2539, 2659, 2671, 2689, 2953
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OFFSET
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1,2
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COMMENTS
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See A037278(n) = concatenation of divisors of n and A176558(n) = reverse concatenation of divisors of n. See A176553, A089374. Sequence of corresponding values of concatenations of divisors of a(n): {1, 13, 17, 113, 131, 197, ...), sequence of corresponding values of reverse concatenations of divisors of a(n): {1, 31, 71, 131, 311, 971, ...).
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LINKS
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Table of n, a(n) for n=1..48.
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EXAMPLE
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a(5) = 31; divisors of 31: 1, 31; both concatenation of divisors 131 and reverse concatenation of divisors 311 are noncomposite.
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CROSSREFS
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Sequence in context: A247895 A336688 A155128 * A077314 A069246 A340870
Adjacent sequences: A176586 A176587 A176588 * A176590 A176591 A176592
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KEYWORD
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nonn,base
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AUTHOR
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Jaroslav Krizek, Apr 21 2010
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EXTENSIONS
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Expanded and revised by Charles R Greathouse IV, Apr 24 2010
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STATUS
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approved
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