A238508 Smallest number m such that 3^m contains a string of n consecutive decreasing integers in its decimal representation.

0, 5, 13, 50, 213, 536, 536, 4582, 63202, 163984

Offset

1,2

Links

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

Example

5 is the smallest exponent such that 3^5 contains two consecutive decreasing integers (3^5 = 243).
13 is the smallest exponent such that 3^13 contains three consecutive decreasing integers (3^13 = 1594323).

Prog

(Python)
def StrDec(x):
..for n in range(10**5):
....count = 0
....i = 0
....string = str(3**n)
....if len(string) == x and x == 1:
......return n
....while i < len(string)-1:
......if int(string[i]) == int(string[i+1])-1:
........count += 1
........i += 1
......else:
........if count >= x-1:
..........return n
........else:
..........count = 0
..........i += 1
....if count >= x-1:
......return n
x = 1
while x < 15:
..print(StrDec(x))
..x += 1

Crossrefs

Cf. A238449, A215727.

Sequence in context: A146689 A146657 A243304 * A151274 A149538 A149539

Adjacent sequences: A238505 A238506 A238507 * A238509 A238510 A238511

Keyword

nonn,base,fini,full

Author

Derek Orr, Feb 27 2014

Extensions

a(9)-a(10) from Giovanni Resta, Mar 02 2014

Status

approved