The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 12:04 EST 2020. Contains 338947 sequences. (Running on oeis4.)