This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A235713 Least number k such that 2^k begins with exactly n identical digits. 1
 1, 25, 143, 1598, 10627, 194220, 26399, 37811757, 15689797, 1609719151, 42001126081, 42116737194, 2277292670319, 8475536580225, 57483036385216, 1185808703658960, 2800250032195382, 203292337502775829, 294180235677139843, 28666496154250702728 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(8) > 200000. The repeating digits that corresponds to a(n) are {2, 3, 1, 1, 1, 1, 7, 1, 3, 1, 1, 7} respectively. a(8) > 3*10^7, a(9) = 15689797 (repeating digit is 3). - Lars Blomberg, Jul 02 2014 LINKS Hiroaki Yamanouchi, Table of n, a(n) for n = 1..100 EXAMPLE 2^25 = 33554432 begins with two identical digits ('33'). Thus a(2) = 25. PROG (Python) def b(n): ..for k in range(1, 2*10**5): ....st = str(2**k) ....count = 0 ....if len(st) >= n: ......for i in range(len(st)): ........if st[i] == st[0]: ..........count += 1 ........else: ..........break ......if count == n: ........return k n = 1 while n < 10: ..print(b(n), end=', ') ..n += 1 CROSSREFS Sequence in context: A147360 A147223 A184057 * A072471 A017042 A100255 Adjacent sequences:  A235710 A235711 A235712 * A235714 A235715 A235716 KEYWORD nonn,base AUTHOR Derek Orr, Jun 13 2014 EXTENSIONS a(8)-a(12) from Hiroaki Yamanouchi, Jul 13 2014 a(13)-a(20) from Hiroaki Yamanouchi, May 31 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 20 17:05 EST 2019. Contains 319335 sequences. (Running on oeis4.)