A039938 - OEIS

%I #16 Apr 27 2017 23:06:38

%S 7,37,237,1789,4357,14379,19587,93957,189572,189572,189597,189597,

%T 189597,1234397,1839597,1958798,1983957,1983957,1983957,1983957,

%U 1983957,1983957,3978594,11983957,19596487,29195397,29195397,29195397

%N Smallest k for which k, 2k, ... nk all contain the digit 7.

%H Giovanni Resta, <a href="/A039938/b039938.txt">Table of n, a(n) for n = 1..125</a>

%e a(2)=37 since 37 and 74 contain a 7.

%t Table[SelectFirst[Range[10^6], Times @@ Boole@ Map[DigitCount[#, 10, 7] > 0 &, # Range@ n] > 0 &], {n, 12}] (* _Michael De Vlieger_, Apr 27 2017, Version 10 *)

%Y Cf. A039932, A039933, A039934, A039935, A039936, A039937, A039939, A039940.

%K base,nonn

%O 1,1

%A _Erich Friedman_

%E More terms from _Patrick De Geest_, Oct 15 1999