This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A369635 #27 Mar 02 2024 13:24:43
%S A369635 0,1,2,3,5,6,7,11,15,19,21,34,46,59,65,102,140,177,202,308,420,532,
%T A369635 606,925,1261,1598,1820,2775,3785,4794,5467,8327,11355,14383,16401,
%U A369635 24982,34066,43151,49205,74946,102200,129453,147622,224840,306600,388360,442866
%N A369635 Numbers in whose base 3-representation every two consecutive digits and every three consecutive digits are distinct.
%C A369635 In other words, the ternary expansion of the number does not contain any string xx or xxx.
%C A369635 The first eleven terms of this sequence comprise the base-3 xenodrome, A023798.
%C A369635 Ordered union of {0}, A037496, A037504, A037512, and A037520.
%e A369635 The base-3 representation of 7 is 21, in which every two consecutive digits are distinct, so 7 is a term of the sequence.
%e A369635 The base-3 representation of 532 is 201201, in which every 3 consecutive digits are distinct, so 532 is a term of the sequence.
%t A369635 s1 = LinearRecurrence[{3, 0, 1, -3}, {0, 1, 3, 11}, 30] (* A037496 *)
%t A369635 s2 = LinearRecurrence[{3, 0, 1, -3}, {0, 1, 5, 15}, 30] (* A037504 *)
%t A369635 s3 = LinearRecurrence[{3, 0, 1, -3}, {0, 2, 6, 19}, 30] (* A037512 *)
%t A369635 s4 = LinearRecurrence[{3, 0, 1, -3}, {0, 7, 21, 65}, 30] (* A037520 *)
%t A369635 s = Union[s1, s2, s3, s4]
%Y A369635 Cf. A023798, A037496, A037504, A037512, and A037520.
%K A369635 nonn,base
%O A369635 1,3
%A A369635 _Clark Kimberling_, Feb 26 2024