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A106370
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Smallest b>1 such that n contains no zeros in its base b representation.
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4
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2, 3, 2, 3, 3, 4, 2, 3, 4, 4, 4, 5, 3, 3, 2, 3, 3, 5, 5, 6, 4, 3, 3, 5, 3, 3, 4, 6, 4, 4, 2, 5, 5, 5, 6, 5, 4, 4, 4, 3, 3, 4, 3, 3, 4, 4, 4, 5, 3, 3, 6, 3, 3, 4, 4, 5, 4, 4, 4, 7, 4, 4, 2, 5, 6, 5, 3, 3, 5, 3, 3, 5, 5, 5, 7, 3, 3, 7, 3, 3, 5, 5, 5, 5, 4, 4, 4, 5, 4, 4, 4, 5, 4, 4, 4, 5, 5, 5, 5, 6, 4, 4, 4, 6, 4
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OFFSET
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1,1
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COMMENTS
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a(n*a(n)+k) <= a(n) for 1<=k<a(n);
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LINKS
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EXAMPLE
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n=20: 20[binary]='101001', 20[ternary]='202',
20[base-4]='110', 20[base-5]='40', all containing at least one zero,
but: 20[base-6]='32', containing no zero therefore a(20)=6.
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PROG
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(Haskell)
a106370 n = f 2 n where
f b x = g x where
g 0 = b
g z = if r == 0 then f (b + 1) n else g z'
where (z', r) = divMod z b
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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