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A244851 Least number k > 0 such that 3^k begins with exactly n consecutive decreasing digits. 3
1, 7, 314, 1655, 11569, 383374, 3052836, 31843469, 458415111, 164840426684 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The leading digit of the resulting powers of 3 are: 3, 2, 6, 4, 6, 7, 8, 7, 8, 9. - Michel Marcus, Jul 11 2014

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

3^7 = 2187 begins with 2 consecutive decreasing digits ('21'). Thus a(2) = 7.

PROG

(Python)

def a(n):

..for k in range(1, 10**5):

....st = str(3**k)

....count = 0

....if len(st) > n:

......for i in range(len(st)):

........if int(st[i]) == int(st[i+1])+1:

..........count += 1

........else:

..........break

......if count == n:

........return k

n = 0

while n < 10:

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

..n += 1

CROSSREFS

Cf. A244848, A244849, A244852.

Sequence in context: A119163 A171148 A219267 * A082160 A220278 A163437

Adjacent sequences:  A244848 A244849 A244850 * A244852 A244853 A244854

KEYWORD

nonn,base,fini,full

AUTHOR

Derek Orr, Jul 07 2014

EXTENSIONS

a(6)-a(10) from Hiroaki Yamanouchi, Jul 11 2014

STATUS

approved

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Last modified July 6 23:01 EDT 2020. Contains 335484 sequences. (Running on oeis4.)