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A244848 Least number k > 0 such that 2^k begins with exactly n consecutive decreasing digits. 3
1, 5, 201, 664, 37025, 78171, 3944467, 138044449, 1910108568, 1641098748 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

2^201 begins "32138760885...". Since it starts with a run of 3 consecutive decreasing digits and 201 is the smallest power to have this property, a(3) = 201.

PROG

(Python)

def a(n):

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

....st = str(2**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. A244849, A244851, A244852.

Sequence in context: A106990 A128791 A303136 * A041775 A093976 A196799

Adjacent sequences:  A244845 A244846 A244847 * A244849 A244850 A244851

KEYWORD

nonn,base,fini,full

AUTHOR

Derek Orr, Jul 07 2014

EXTENSIONS

a(7)-a(10) from Hiroaki Yamanouchi, Jul 10 2014

STATUS

approved

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Last modified March 23 05:36 EDT 2019. Contains 321422 sequences. (Running on oeis4.)