|
| |
|
|
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; 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
| 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
|
|
|
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: A176364 A029831 A203885 * A016824 A016860 A016980
Adjacent sequences: A064866 A064867 A064868 * A064870 A064871 A064872
|
|
|
KEYWORD
| base,easy,nonn
|
|
|
AUTHOR
| Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Oct 09 2001
|
| |
|
|
