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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
OFFSET
1,1
CROSSREFS
KEYWORD
sign,base
AUTHOR
V. Raman, Sep 07 2012
STATUS
approved