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 A216479 a(n) is the least multiple of n which uses only the digit 1, or a(n) = -1 if no such multiple exists. 1
 1, -1, 111, -1, -1, -1, 111111, -1, 111111111, -1, 11, -1, 111111, -1, -1, -1, 1111111111111111, -1, 111111111111111111, -1, 111111, -1, 1111111111111111111111, -1, -1, -1, 111111111111111111111111111, -1, 1111111111111111111111111111, -1, 111111111111111, -1, 111111, -1, -1, -1, 111, -1, 111111, -1, 11111, -1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) = -1 if and only if n is a multiple of 2 or 5. See comment in A216485. - Chai Wah Wu, Jun 21 2015 LINKS Chai Wah Wu, Table of n, a(n) for n = 1..1000 CROSSREFS Cf. A004290, A079339, A181060, A181061. Sequence in context: A280142 A077573 A266435 * A123698 A123727 A282915 Adjacent sequences:  A216476 A216477 A216478 * A216480 A216481 A216482 KEYWORD sign,base AUTHOR V. Raman, Sep 07 2012 STATUS approved

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Last modified August 15 13:10 EDT 2020. Contains 336504 sequences. (Running on oeis4.)