

A102691


Least nexpodigital number (i.e., numbers m such that m^n has exactly n decimal digits).


1



0, 4, 5, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
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OFFSET

1,2


COMMENTS

10^(n1) being the smallest ndigit number, nexpodigital numbers exist iff 10^(n1) < 9^n, i.e., iff n1 < 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 21expodigital.


LINKS

Table of n, a(n) for n=1..21.


FORMULA

a(n) = 10  A102690(n).


EXAMPLE

a(3)=5 because this is the first number followed by 6,7,8 and 9 which are all 3expodigital: 5^3 = 125; 6^3 = 216; 7^3 = 343; 8^3 = 512; 9^3 = 729.


CROSSREFS

Cf. A102690.
Essentially the same as A067471.  R. J. Mathar, Aug 30 2008
Sequence in context: A244586 A114546 A067471 * A014553 A227422 A121855
Adjacent sequences: A102688 A102689 A102690 * A102692 A102693 A102694


KEYWORD

fini,full,nonn,base,changed


AUTHOR

Lekraj Beedassy, Jan 21 2005


EXTENSIONS

Edited by Charles R Greathouse IV, Aug 03 2010


STATUS

approved



