A244852 Least number k > 0 such that 3^k begins with exactly n consecutive increasing digits.

1, 17, 149, 146, 7997, 45419, 3972963, 27487124, 406680034

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Example

3^17 = 129140163 begins with 2 consecutive increasing digits ('12'). Thus a(2) = 17.

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, A244851.

Sequence in context: A196780 A208506 A299599 * A064102 A161497 A162328

Adjacent sequences: A244849 A244850 A244851 * A244853 A244854 A244855

Keyword

nonn,base,fini,full

Author

Derek Orr, Jul 07 2014

Extensions

a(7)-a(9) from Hiroaki Yamanouchi, Jul 10 2014

Status

approved