%I
%S 0,1,2,3,4,5,6,8,9,10,11,12,13,15,16,17,18,19,20,22,23,24,25,26,27,29,
%T 30,31,32,33,34,37,38,39,40,41,48,49,51,52,53,54,55,56,58,59,60,61,62,
%U 63,65,66,67,68,69,70,73,74,75,76,77,78,80
%N Numbers in which every string of 2 consecutive base 6 digits contains exactly 2 distinct numbers.
%t Select[Range[0,80],FreeQ[Differences[IntegerDigits[#,6]],0]&] (* _Harvey P. Dale_, Sep 09 2016 *)
%Y Cf. A000975 (base2 analog), A031941 or A043089 (base3 analog), A031942 or A043090 (base4 analog), A031943 or A043091 (base5 analog), A043093, ..., A043096 (base7 through base10 analog).
%K nonn,base
%O 1,3
%A _Clark Kimberling_
