A039938 Smallest k for which k, 2k, ... nk all contain the digit 7.

7, 37, 237, 1789, 4357, 14379, 19587, 93957, 189572, 189572, 189597, 189597, 189597, 1234397, 1839597, 1958798, 1983957, 1983957, 1983957, 1983957, 1983957, 1983957, 3978594, 11983957, 19596487, 29195397, 29195397, 29195397

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..125

Example

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

Mathematica

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 *)

Crossrefs

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

Sequence in context: A339686 A144496 A025012 * A285846 A102760 A332906

Adjacent sequences: A039935 A039936 A039937 * A039939 A039940 A039941

Keyword

base,nonn

Author

Erich Friedman

Extensions

More terms from Patrick De Geest, Oct 15 1999

Status

approved