Search: id:A102691
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%I A102691
%S A102691 0,4,5,6,7,7,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9
%N A102691 Least n-expodigital number (i.e. numbers m such that m^n has exactly 
               n digits).
%C A102691 a(n)= 10 - A102690(n).
%C A102691 10^(n-1) being the smallest n-digit number, n-expodigital numbers exist 
               iff 10^(n-1) < 9^n,i.e.,iff n-1 < n*log_10(9);this condition holds 
               for all n up to 21 because beyond we have, for instance,20 < 22*log_10(9) 
               < 21. Thus numbers can be at most 21-expodigital.
%C A102691 Essentially the same as A067471. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Aug 30 2008]
%e A102691 a(3)=5 because this is the first number followed by 6,7,8 and 9 which 
               are all 3-expodigital:5^3=125; 6^3=216; 7^3=343; 8^3=512; 9^3=729.
%Y A102691 Cf. A102690.
%Y A102691 Sequence in context: A163875 A114546 A067471 this_sequence A014553 A121855 
               A090925
%Y A102691 Adjacent sequences: A102688 A102689 A102690 this_sequence A102692 A102693 
               A102694
%K A102691 fini,full,nonn
%O A102691 1,2
%A A102691 Lekraj Beedassy (blekraj(AT)yahoo.com), Jan 21 2005

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