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A085610
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Least m ending in 1 such that m^n ends in a string of n 0's followed by the final 1.
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2
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101, 251, 10001, 18751, 200001, 4218751, 100000001, 74218751, 10000000001, 3574218751, 1000000000001, 163574218751, 100000000000001, 480163574218751, 2000000000000001, 6230163574218751, 1000000000000000001
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OFFSET
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1,1
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COMMENTS
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a(n) = 10^(n+1)+1 if n and 10 are coprime.
a(5*k) = 2*10^(5*k)+1 if k and 10 are coprime. (End)
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LINKS
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EXAMPLE
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We have a(4)=18751 because the latter is the shortest number whose fourth power ends in 00001; Actually,18751^4=123622560703200001.
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MAPLE
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f:= proc(n) local z, R;
if igcd(n, 10)=1 then return 10^(n+1)+1 fi;
min(select(t -> t mod 10 = 1, map(rhs@op, {msolve(z^n=1, 10^(n+1))} minus {{z=1}})));
end proc:
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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