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%I #27 Jan 28 2020 12:38:01
%S 0,1,43,43,314,314,2354,8555,13326,81784,279272,865356,1727602,1727602
%N Least k such that 2^k has at least n consecutive 2's in its decimal representation.
%H Popular Computing (Calabasas, CA), <a href="/A094776/a094776.jpg">Two Tables</a>, Vol. 1, (No. 9, Dec 1973), page PC9-16.
%e a(3)=43 because 2^43 (i.e. 8796093022208) is the smallest power of 2 to contain a run of 3 consecutive twos in its decimal form.
%t Table[k = 0; While[! SequenceCount[IntegerDigits[2^k], ConstantArray[2, n]] > 0, k++]; k, {n, 10}] (* _Robert Price_, May 17 2019 *)
%o (Python)
%o def A259089(n):
%o ....s, k, k2 = '2'*n, 0, 1
%o ....while True:
%o ........if s in str(k2):
%o ............return k
%o ........k += 1
%o ........k2 *= 2 # _Chai Wah Wu_, Jun 19 2015
%Y Cf. A006889, A131535, A131536, A063565, A259091, A259092.
%K more,nonn,base
%O 0,3
%A _N. J. A. Sloane_, Jun 18 2015
%E a(7)-a(13) from _Chai Wah Wu_, Jun 20 2015
%E Definition corrected by _Manfred Scheucher_, Jun 23 2015
%E a(0) prepended by _Chai Wah Wu_, Jan 28 2020
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