%I
%S 0,1,2,3,4,5,6,7,9,10,11,12,13,14,15,17,18,19,20,21,22,23,25,26,27,28,
%T 29,30,31,33,34,35,36,37,38,39,41,42,43,44,45,46,47,50,51,52,53,54,55,
%U 63,64,66,67,68,69,70,71,72,74,75,76,77,78
%N Every string of 2 consecutive base 7 digits contains exactly 2 distinct numbers.
%Y Cf. A000975 (base2 analog), A031941 or A043089 (base3 analog), A031942 or A043090 (base4 analog), A031943 or A043091 (base5 analog), A043092, ..., A043096 (base6 through base10 analog).
%K nonn,base
%O 0,3
%A _Clark Kimberling_
