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 A258004 #12 Jul 06 2015 23:40:51
%S A258004 0,63,990,3822,15222,15738,15804,60858,62394,62940,224694,241110,
%T A258004 241338,243162,243420,244188,249306,249318,249564,249660,251370,
%U A258004 251628,251634,252396,252660,252792,964314,964326,965340,972522,972636,973548,976620,990678,995034,995046,997098,997212,998124,998130,1003242,1005420
%N A258004 Capless binary boundary codes for holeless strictly non-overlapping polyhexes, only the maximal representative from each equivalence class obtained by rotating.
%C A258004 Indexing starts from zero, because a(0) = 0 is a special case, indicating an empty path, which thus ends at the same vertex as where it started from.
%H A258004 Antti Karttunen, <a href="/A258004/b258004.txt">Table of n, a(n) for n = 0..874</a>
%F A258004 a(n) = A053645(A258003(n)).
%e A258004 63 ("111111" in binary) is present as it encodes a single hex. This is because when we walk in honeycomb-lattice from vertex to vertex, at each vertex turning to the same direction, we will return to the starting vertex after enclosing a hex with six such steps.
%o A258004 (Scheme)
%o A258004 (define (A258004 n) (A053645 (A258003 n)))
%Y A258004 Cf. A053645, A258003.
%Y A258004 Subsequence of A255561 and A258014.
%K A258004 nonn,base
%O A258004 0,2
%A A258004 _Antti Karttunen_, May 16 2015