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A243295 Least number k > 0 such that 3^k contains an n-digit long substring of the infinite string "0123456789012345678901234567890123456..." 1
1, 8, 15, 57, 102, 332, 2345, 2345, 10110, 118745, 127188, 326758, 2258910 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(n) is an increasing (but not necessarily strictly increasing) sequence.
a(7) = 4849 if all numbers were distinct.
By A238507, a(10) <= 200633.
LINKS
EXAMPLE
3^8 = 6561 contains a subsequence of the infinite string in the definition ('56'). Thus a(2) = 8.
PROG
(Python)
def a(n):
..for k in range(1, 10**5):
....for i in range(10):
......s = ''
......for j in range(i, i+n):
........dig=j%10
........s+=str(dig)
......if str(3**k).find(s) > -1:
........return k
n=1
while n < 10:
..print(a(n))
..n+=1
CROSSREFS
Cf. A238507.
Sequence in context: A362906 A350442 A151792 * A118526 A167340 A037377
KEYWORD
nonn,hard,base,more
AUTHOR
Derek Orr, Jun 02 2014
EXTENSIONS
a(10)-a(12) from Hiroaki Yamanouchi, Sep 26 2014
a(13) from Chai Wah Wu, Jun 14 2020
STATUS
approved

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Last modified March 29 09:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)