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A061724
Smallest number which has more different digits than its n-th power, or -1 if no such number exists.
0
109, 1920, 26730, 4385270, 13486709, 13652048, 134267085, 285963417, 341872690, 1032479568, 1026349857, 1027563984, 1029637584, 1239574806, 2059716348, 1654923078, 58157032649, 8152497360, 17345693802, 127601348591
OFFSET
2,1
COMMENTS
a(22), a(23), a(24) > 2*10^11, if they exist. - Giovanni Resta, Aug 06 2019
EXAMPLE
1920 is the smallest number which has more different digits than its cube (4 digits vs. 3 digits in 7077888000 = 1920^3), hence a(3) = 1920
PROG
(Python)
from itertools import count
def a(n): return next(k for k in count(1) if len(set(str(k))) > len(set(str(k**n))))
print([a(n) for n in range(2, 6)]) # Michael S. Branicky, May 25 2023
CROSSREFS
Sequence in context: A262854 A232118 A201849 * A145852 A232198 A232416
KEYWORD
nonn,base,hard,more
AUTHOR
Ulrich Schimke (ulrschimke(AT)aol.com)
EXTENSIONS
a(6) and a(7) from Stefan Steinerberger, Sep 07 2007
a(8)-a(17) from Sean A. Irvine, Dec 02 2010
a(18)-a(21) from Giovanni Resta, Aug 06 2019
STATUS
approved