

A051248


n^a(n) is the smallest power of n (with a(n) > 1) which starts with n.


10



2, 8, 18, 6, 24, 10, 20, 11, 22, 2, 26, 14, 10, 8, 92, 6, 166, 5, 19, 11, 60, 39, 48, 51, 94, 42, 467, 86, 14, 66, 58, 3, 5268, 33, 58, 10, 45, 70, 23, 6, 205, 70, 31, 15, 50, 84, 248, 70, 72, 94, 107, 170, 30, 10139, 182, 136, 87, 318, 49, 10, 178, 237, 295, 99, 17, 206
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OFFSET

1,1


COMMENTS

The largest of the first 10000 terms is a(1955) = 119589011.  Giovanni Resta, May 27 2016


LINKS



EXAMPLE

2^8 = 256 begins with 2, and 2^k does not begin with 2 for any smaller integer k > 1, so a(2) = 8.


MATHEMATICA

f[n_]:=Module[{i=2}, While[Take[IntegerDigits[n^i], IntegerLength[n]] != IntegerDigits[n], i++]; i]; Array[f, 70] (* Harvey P. Dale, Oct 04 2011 *)


PROG

(Haskell)
import Data.List (isPrefixOf)
a051248 n = 2 + length
(takeWhile (not . (show n `isPrefixOf`) . show) $ iterate (* n) (n^2))


CROSSREFS



KEYWORD

nonn,base,nice


AUTHOR



EXTENSIONS



STATUS

approved



