A270043 a(n) = Smallest m >= 15 containing no sevens when represented in any base from 8 through n.

16, 17, 18, 19, 20, 21, 22, 24, 24, 26, 26, 28, 28, 30, 30, 32, 32, 36, 36, 36, 36, 38, 38, 42, 42, 42, 42, 44, 44, 48, 48, 48, 48, 50, 50, 54, 54, 54, 54, 386, 386, 396, 400, 426, 426, 426, 515, 515, 515, 515, 515, 515, 515, 515, 515, 515, 515, 528

Offset: 8

Author

Nathan Fox, Mar 09 2016

Keywords

• nonn
• base

Comments

It remains to be determined if the sequence is finite.

Links

• Nathan Fox, Table of n, a(n) for n = 8..227

Crossrefs

Cf. A270033, A270037, A270038, A216192, A270039, A270040, A270041, A270042, A270044, A270045.

Programs

Mathematica

Table[SelectFirst[Range[15, 10^3], Total@ Map[Function[k, DigitCount[#, k, 7]], Range[8, n]] == 0 &], {n, 8, 65}] /. n_ /; MissingQ@ n -> Nothing (* Michael De Vlieger, Mar 10 2016, Version 10.2 *)