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A215728 a(n) is the smallest m for which 5^m contains n consecutive identical digits.

%I A215728 #26 Apr 18 2020 08:05:06
%S A215728 0,11,50,95,125,1087,2786,2790,2796,2797,2802,2803,1040703,5547565,
%T A215728 7761841,17876345
%N A215728 a(n) is the smallest m for which 5^m contains n consecutive identical digits.
%C A215728 a(13) > 893000. - _Chai Wah Wu_, Dec 17 2014
%o A215728 (Python)
%o A215728 def A215728(n):
%o A215728     l, x = [str(d)*n for d in range(10)], 1
%o A215728     for m in range(10**9):
%o A215728         s = str(x)
%o A215728         for k in l:
%o A215728             if k in s:
%o A215728                 return m
%o A215728         x *= 5
%o A215728     return 'search limit reached'
%o A215728 # _Chai Wah Wu_, Dec 17 2014
%Y A215728 Cf. A215734, A045875.
%K A215728 nonn,base,more
%O A215728 1,2
%A A215728 _V. Raman_, Aug 22 2012
%E A215728 a(13)-a(14) from _Giovanni Resta_, Apr 19 2016
%E A215728 a(15)-a(16) from _Bert Dobbelaere_, Feb 13 2019