login
Smallest multiple of A047201(n) (i.e., numbers not divisible by 5) with only digits 6 and 7.
0

%I #13 Feb 13 2024 11:41:27

%S 67,76,6777,76,7776,6776,776,6777,6677,7776,676,6776,7776,6766,7776,

%T 76,67767,6776,667,7776,676,6777,6776,667,67766,7776,66777777,6766,

%U 7776,666777,76,77766,7667,76776,676777,6776,67666,667776,7776,67767,67677

%N Smallest multiple of A047201(n) (i.e., numbers not divisible by 5) with only digits 6 and 7.

%H Nick Hobson, <a href="https://web.archive.org/web/20160802192115/http://www.qbyte.org/puzzles/p080s.html">Solution to Puzzle 80:"Sixes and sevens" (generalization of)</a>

%t f[n_] := Block[{k = n},While[Union @ IntegerDigits[k] != {6, 7}, k += n];k];f /@ Select[Range[52], Mod[ #, 5] > 0 &] (* _Ray Chandler_, Dec 18 2006 *)

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Dec 17 2006

%E Corrected and extended by _Ray Chandler_, Dec 18 2006