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 A216481 a(n) is the least multiple of n which uses only digit 2, or a(n) = -1 if no such multiple exists. 2
 2, 2, 222, -1, -1, 222, 222222, -1, 222222222, -1, 22, -1, 222222, 222222, -1, -1, 2222222222222222, 222222222, 222222222222222222, -1, 222222, 22, 2222222222222222222222, -1, -1, 222222, 222222222222222222222222222, -1, 2222222222222222222222222222, -1, 222222222222222, -1, 222222, 2222222222222222, -1, -1, 222, 222222222222222222, 222222, -1, 22222, 222222 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS CROSSREFS Cf. A004290, A078241, A079339, A181060, A181061, A216812. Sequence in context: A003110 A100956 A304915 * A078241 A216812 A068103 Adjacent sequences:  A216478 A216479 A216480 * A216482 A216483 A216484 KEYWORD sign,base AUTHOR V. Raman, Sep 07 2012 STATUS approved

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Last modified December 14 01:22 EST 2019. Contains 329978 sequences. (Running on oeis4.)