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A235869 Least number k such that 3^k begins with exactly n identical digits. 1
1, 19, 33, 2061, 6563, 17853, 2319050, 2061700, 57587802, 2725111202, 6121395677, 79432391610, 5689239922828, 9667911135850, 253066675679888, 959406299366116, 2267148455007422, 182092146481798583, 1074950828335499452, 3586769629515088106, 72389675081649855753 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

a(12) > 2 * 10^10 - Hiroaki Yamanouchi, Jul 13 2014

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 1..100

EXAMPLE

3^19 = 1162261467 begins with two identical digits ('11'). Thus a(2) = 19.

PROG

(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

CROSSREFS

Sequence in context: A223608 A146438 A146571 * A140601 A031206 A214231

Adjacent sequences:  A235866 A235867 A235868 * A235870 A235871 A235872

KEYWORD

nonn,base

AUTHOR

Derek Orr, Jun 13 2014

EXTENSIONS

a(7)-a(11) from Hiroaki Yamanouchi, Jul 13 2014

a(12)-a(21) from Hiroaki Yamanouchi, May 31 2015

STATUS

approved

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Last modified June 25 22:13 EDT 2022. Contains 354868 sequences. (Running on oeis4.)