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A235869
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Least number k such that 3^k begins with exactly n identical digits.
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1
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1, 19, 33, 2061, 6563, 17853, 2319050, 2061700, 57587802, 2725111202, 6121395677, 79432391610, 5689239922828, 9667911135850, 253066675679888, 959406299366116, 2267148455007422, 182092146481798583, 1074950828335499452, 3586769629515088106, 72389675081649855753
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OFFSET
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1,2
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COMMENTS
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a(7) > 200000.
The repeating digits that correspond to these data values are {3, 1, 5, 2, 2, 1, 1, 7, 2, 8, 1} respectively.
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LINKS
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EXAMPLE
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3^19 = 1162261467 begins with two identical digits ('11'). Thus a(2) = 19.
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PROG
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(Python)
def b(n):
..for k in range(1, 2*10**5):
....st = str(3**k)
....count = 0
....if len(st) >= n:
......for i in range(len(st)):
........if st[i] == st[0]:
..........count += 1
........else:
..........break
......if count == n:
........return k
n = 1
while n < 10:
..print(b(n), end=', ')
..n += 1
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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