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A064869 The minimal number which has multiplicative persistence 5 in base n. 15
244140624, 3629, 1601, 1535, 394, 679, 317, 1099, 127, 135, 582, 187, 168, 157, 201, 159, 230, 215, 180, 185, 246, 181, 188, 195, 198, 323, 239, 255, 259, 267, 239, 287, 295, 293, 310, 313, 280, 377, 375, 395, 347, 360, 321, 370, 439, 431, 458, 355, 362 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

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) seem not to exist.

LINKS

Table of n, a(n) for n=5..53.

M. R. Diamond and D. D. Reidpath, A counterexample to a conjecture of Sloane and Erdos, J. Recreational Math., 1998 29(2), 89-92.

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

FORMULA

a(n) = 6*n-[n/120] for n > 119

EXAMPLE

a(9)=394 because 394=[477]->[237]->[46]->[26]->[13]->[3] and no smaller n has persistence 5 in base 9.

CROSSREFS

Cf. A003001, A031346, A064867, A064868, A064870, A064871, A064872.

Sequence in context: A289981 A203885 A234058 * A016824 A016860 A016980

Adjacent sequences:  A064866 A064867 A064868 * A064870 A064871 A064872

KEYWORD

base,easy,nonn

AUTHOR

Sascha Kurz, Oct 09 2001

STATUS

approved

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Last modified August 18 10:51 EDT 2017. Contains 290710 sequences.