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 A244849 Least number k > 0 such that 2^k begins with exactly n consecutive increasing digits. 3
 1, 7, 90, 155, 8290, 63293, 4338436, 5194868, 62759188 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The leading digit of the resulting powers of 2 are: 2, 1, 1, 4, 3, 1, 2, 1, 1. - Michel Marcus, Jul 11 2014 LINKS EXAMPLE 2^7 = 128 begins with 2 consecutive increasing digits ('12'). Thus a(2) = 7. 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. A244848, A244851, A244852. Sequence in context: A142995 A200832 A103064 * A321164 A243699 A007820 Adjacent sequences:  A244846 A244847 A244848 * A244850 A244851 A244852 KEYWORD nonn,base,fini,full AUTHOR Derek Orr, Jul 07 2014 EXTENSIONS a(7)-a(9) from Hiroaki Yamanouchi, Jul 10 2014 STATUS approved

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Last modified March 22 17:25 EDT 2019. Contains 321422 sequences. (Running on oeis4.)