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A064867
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The minimal number which has multiplicative persistence 3 in base n.
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7
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26, 63, 68, 23, 27, 31, 35, 39, 43, 46, 50, 54, 58, 62, 66, 69, 73, 77, 81, 85, 89, 92, 96, 100, 104, 108, 112, 115, 119, 123, 127, 131, 135, 138, 142, 146, 150, 154, 158, 161, 165, 169, 173, 177, 181, 184, 188, 192
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OFFSET
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3,1
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COMMENTS
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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.
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LINKS
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Table of n, a(n) for n=3..50.
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) = 4*n-[n/6] for n > 5
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EXAMPLE
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a(3)=26 because 26=[222]->[22]->[11]->[1] and no fewer n has persistence 3 in base 3.
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CROSSREFS
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Cf. A003001, A031346, A064868, A064869, A064870, A064871, A064872.
Sequence in context: A039413 A043236 A044016 * A020155 A063304 A199849
Adjacent sequences: A064864 A064865 A064866 * A064868 A064869 A064870
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KEYWORD
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base,easy,nonn
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AUTHOR
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Sascha Kurz, Oct 08 2001
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STATUS
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approved
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