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Search: id:A110751
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| A110751 |
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Numbers n such that n and its digital reversal have same prime divisors. |
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+0
10
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Contains the palindromes A002113 as a subsequence. 1089 and 2178 are the first two non-palindromic terms. Any number of concatenations of 1089 with itself or 2178 with itself gives a term e.g. 10891089 etc. Hence there are infinitely many non-palindromic terms. They are given in A110819.
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EXAMPLE
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1089 = 3^2*11^2, 9801 = 3^4*11^2.
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MATHEMATICA
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Select[ Range[ 500], First /@ FactorInteger[ # ] == First /@ FactorInteger[ FromDigits[ Reverse[ IntegerDigits[ # ]]]] &] (* Robert G. Wilson v *)
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PROGRAM
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(PARI) is_A110751(n)={ local(r=eval(concat(vecextract(Vec(Str(n)), "-1..1")))); r==n || factor(r)[, 1]==factor(n)[, 1] } /* M. F. Hasler */
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CROSSREFS
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Cf. A002113, A110819.
Sequence in context: A044821 A048307 A043713 this_sequence A147882 A002113 A084982
Adjacent sequences: A110748 A110749 A110750 this_sequence A110752 A110753 A110754
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KEYWORD
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base,easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 11 2005
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Sep 21 2005
Corrected comment, added PARI code. - M. F. Hasler (MHasler(AT)univ-ag.fr), Nov 16 2008
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