A270040 a(n) = Smallest m >= 9 containing no fours when represented in any base from 5 through n.

10, 11, 12, 13, 15, 15, 17, 17, 66, 75, 75, 86, 86, 90, 138, 138, 138, 138, 138, 138, 138, 138, 138, 182, 182, 182, 182, 182, 182, 182, 182, 182, 185, 781817578165, 781817578165, 7826560751018861596150680

Offset: 5

Author

Nathan Fox, Mar 09 2016

Keywords

• nonn
• base

Comments

It remains to be determined if the sequence is finite.

These numbers are not very Foury, at least not initially. (See A268236.)

Links

• Nathan Fox, Table of n, a(n) for n = 5..59

Crossrefs

Cf. A268236, A268237, A270030, A270037, A270038, A216192, A270039, A270041, A270042, A270043, A270044, A270045.

Programs

Mathematica

Table[SelectFirst[Range[9, 10^3], Total@ Map[Function[k, DigitCount[#, k, 4]], Range[5, n]] == 0 &], {n, 5, 60}] /. n_ /; MissingQ@ n -> Nothing (* Michael De Vlieger, Mar 10 2016, Version 10.2 *)