Smallest k for which k, 2k, ... nk all contain the digit 6.

Terms

a(0) =6a(1) =63a(2) =563a(3) =1563a(4) =1632a(5) =3216a(6) =12316a(7) =23266a(8) =66321a(9) =66321a(10) =76923a(11) =76923a(12) =156328a(13) =280692a(14) =566331a(15) =566331a(16) =566331a(17) =2307692a(18) =2307692a(19) =2307692a(20) =2307692a(21) =2307692a(22) =2307692a(23) =2307692a(24) =2307692a(25) =11533664a(26) =23306676a(27) =23306676a(28) =23306676a(29) =23306676