a(n) is the least multiple of n which uses only digits 1 and 2. a(n) = -1 if no such multiple exists.
A216478
a(n) is the least multiple of n which uses only digits 1 and 2. a(n) = -1 if no such multiple exists.
Terms
- a(0) =1a(1) =2a(2) =12a(3) =12a(4) =-1a(5) =12a(6) =21a(7) =112a(8) =12222a(9) =-1a(10) =11a(11) =12a(12) =221a(13) =112a(14) =-1a(15) =112a(16) =221a(17) =12222a(18) =1121a(19) =-1a(20) =21a(21) =22a(22) =12121a(23) =2112a(24) =-1a(25) =1222a(26) =21222a(27) =112a(28) =12122a(29) =-1
External references
- oeis: A216478