

A130081


Smallest number whose seventh power has at least n digits.


2



1, 2, 2, 3, 4, 6, 8, 10, 14, 20, 27, 38, 52, 72, 100, 139, 194, 269, 373, 518, 720, 1000, 1390, 1931, 2683, 3728, 5180, 7197, 10000, 13895, 19307, 26827, 37276, 51795, 71969, 100000, 138950, 193070, 268270, 372760, 517948, 719686, 1000000, 1389496
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OFFSET

1,2


COMMENTS

Powers of seventh root of 10 rounded up.


LINKS



FORMULA

a(n) = ceiling(10^((n1)/7)).


EXAMPLE

1^7 = 1 has 1 digit, 2^7 = 128 has three digits, hence a(2) = a(3) = 2.


MATHEMATICA



PROG

(Magma) [ Ceiling(Root(10^(n1), 7)): n in [1..44] ];


CROSSREFS

Cf. A011557 (powers of 10), A017936 (smallest number whose square has n digits), A018005 (smallest number whose cube has n digits), A018074 (smallest number whose fourth power has n digits), A018143 (smallest number whose fifth power has n digits), A130080 to A130084 (smallest number whose sixth ... tenth power has n digits).


KEYWORD

nonn,base,easy


AUTHOR



STATUS

approved



