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A244859
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Least positive multiple of n which when written in base 10 is either a repunit or of the form 1111....0000.
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3
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0, 1, 10, 111, 100, 10, 1110, 111111, 1000, 111111111, 10, 11, 11100, 111111, 1111110, 1110, 10000, 1111111111111111, 1111111110, 111111111111111111, 100, 111111, 110, 1111111111111111111111, 111000, 100, 1111110, 111111111111111111111111111, 11111100
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OFFSET
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0,3
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COMMENTS
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LINKS
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MAPLE
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d2:= padic:-ordp(n, 2);
d5:= padic:-ordp(n, 5);
m:= n/2^d2/5^d5;
10^max(d2, d5)*(10^numtheory:-order(10, 9*m)-1)/9
end proc:
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PROG
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(Python)
def a(n):
if n == 0: return 0
moddict = {0: 0}
for e in range(1, n+2):
repe = (10**e-1)//9
r = repe%n
if r in moddict:
return repe - moddict[r]
else:
moddict[r] = repe
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CROSSREFS
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Equal to A004290 for the first 7 terms.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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