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Search: id:A064868
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| A064868 |
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The minimal number which has multiplicative persistence 4 in base n. |
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+0
7
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| 2344, 172, 131, 174, 52, 77, 75, 83, 75, 81, 89, 95, 101, 104, 110, 133, 143, 127, 133, 119, 124, 129, 134, 139, 144, 149, 154, 159, 164, 169, 174, 179, 184, 189, 194, 199, 204, 209, 214, 219, 224, 229, 234, 238, 243, 248, 253, 258, 263, 268, 273, 278, 283
(list; graph; listen)
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OFFSET
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5,1
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COMMENT
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The persistence of a number is the number of times you need to multiply the digits together before reaching a single digit. a(3) and a(4) do not seem to exist.
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LINKS
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M. R. Diamond and D. D. Reidpath, A counterexample to a conjuncture of Sloane and Erdos, J. Recreational Math., 1998 29(2), 89-92. [Broken link?]
Sascha Kurz, Persistence in different bases
C. Rivera, Minimal prime with persistence p
N. J. A. Sloane, The persistence of a number, J. Recreational Math., 6 (1973), 97-98.
Eric Weisstein's World of Mathematics, Multiplicative Persistence
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FORMULA
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a(n) = 5*n-[n/24] for n > 23
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EXAMPLE
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a(6)=172 because 172=[444]->[144]->[24]->[12]->[2], and no fewer n has persistence 4 in base 6.
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CROSSREFS
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Cf. A003001, A031346, A064867, A064869, A064870, A064871, A064872.
Sequence in context: A043440 A023938 A132204 this_sequence A045306 A003552 A130023
Adjacent sequences: A064865 A064866 A064867 this_sequence A064869 A064870 A064871
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KEYWORD
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base,easy,nonn
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AUTHOR
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Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Oct 09 2001
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