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 A059143 #12 Sep 13 2022 09:31:28
%S A059143 4,7,4,7,10,7,4,7,4,10,13,10,4,7,4,7,10,7,4,7,4,13,16,13,4,7,4,7,10,7,
%T A059143 4,7,4,10,13,10,4,7,4,7,10,7,4,7,4,16,19,16,4,7,4,7,10,7,4,7,4,10,13,
%U A059143 10,4,7,4,7,10,7,4,7,4,13,16,13,4,7,4,7,10,7,4,7,4,10,13,10,4,7,4,7,10
%N A059143 A hierarchical sequence (W3{2,2}*c - see A059126).
%H A059143 Jonas Wallgren, <a href="/A059126/a059126.txt">Hierarchical sequences</a>
%F A059143 a(n) = A059131(3*n) + A059131(3*n+1) + A059131(3*n+2). - _Sean A. Irvine_, Sep 13 2022
%Y A059143 Cf. A001511, A059126, A059131, A059144, A059145.
%K A059143 easy,nonn
%O A059143 0,1
%A A059143 _Jonas Wallgren_, Jan 19 2001