Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 May 09 2023 13:14:40
%S 25,31,74,80,123,129,172,175,217,227,270,276,319,325,368,374,417,423,
%T 466,472,515,518,560,570,613,619,662,668,711,717,760,766,809,815,858,
%U 861,903,913,956,962,1005,1011,1054,1060,1103
%N Numbers k such that 3 and 4 occur juxtaposed in the base-7 representation of k but not of k-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{3,4}]>0 || SequenceCount[ IntegerDigits[n,7],{4,3}]>0,1,0],{n,1200}],{0,1}][[;;,2]] (* _Harvey P. Dale_, May 09 2023 *)
%Y Cf. A007093.
%K nonn,base
%O 1,1
%A _Clark Kimberling_