

A045875


a(n) is the smallest m for which the decimal representation of 2^m contains n consecutive identical digits.


26



0, 16, 24, 41, 220, 971, 972, 8554, 42485, 42486, 271979, 1039315, 1727602, 6855865, 63416789, 106892452
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OFFSET

1,2


COMMENTS



LINKS



MATHEMATICA

a[n_] := Block[{k = 0}, While[ !MemberQ[ Length /@ Split@ IntegerDigits[2^k], n], k++ ]; k]; Table[a[n], {n, 6}] (* Robert G. Wilson v, Oct 21 2010 *)


PROG

(Python)
l, x = [str(d)*n for d in range(10)], 1
for m in range(10**9):
s = str(x)
for k in l:
if k in s:
return m
x *= 2
return 'search limit reached'


CROSSREFS



KEYWORD

base,nonn,hard,more


AUTHOR



EXTENSIONS



STATUS

approved



