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A248018 Least number k > 0 such that n^k contains n*R_n in its decimal representation, or 0 if no such k exists. 0
1, 43, 119, 96, 186, 1740, 6177, 8421, 104191, 0, 946417 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

R_n is the repunit of length n, i.e., R_n = (10^n-1)/9, A002275.

a(10^n) = 0 for all n > 0. - Derek Orr, Sep 29 2014

a(9) > 86000. - Derek Orr, Sep 29 2014

Note that a(2) = A030000(22), and a(3) = A063566(333), and that sequence is also related in a similar way to sequences from A063567 up to A063572. - Michel Marcus, Sep 30 2014

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

a(2) = 43 because 2^43 = 8796093022208 has the string '22' in it and 43 is the smallest power of 2 that produces such a result.

a(3) = 119 because 3^119 = 599003433304810403471059943169868346577158542512617035467 contains the string '333', and 119 is the smallest power of 3 that gives us such a result.

PROG

(Python)

def a(n):

..s = str(n)

..p = len(s)

..if s.count('1') == 1 and s.count('0') == p - 1:

....return 0

..k = 1

..while not str(n**k).count(n*s):

....k += 1

..return k

n = 1

while n < 10:

..print(a(n), end=', ')

..n += 1

# Derek Orr, Sep 29 2014

CROSSREFS

Cf. A002275.

Sequence in context: A297412 A282294 A251075 * A262491 A029816 A044294

Adjacent sequences:  A248015 A248016 A248017 * A248019 A248020 A248021

KEYWORD

base,nonn,hard,more

AUTHOR

Talha Ali, Sep 29 2014

EXTENSIONS

a(3) and a(5) corrected, a(6)-a(8) added by Derek Orr, Sep 29 2014

a(4) corrected and a(9)-a(11) added by Hiroaki Yamanouchi, Oct 01 2014

STATUS

approved

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Last modified September 24 18:11 EDT 2022. Contains 356949 sequences. (Running on oeis4.)