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 A291073 #10 Dec 12 2023 13:40:08
%S A291073 -1,21,1,1,221,221,11,11,11,11,2221,2221,2221,2221,111,211,111,211,
%T A291073 111,211,111,211,12221,22221,12221,22221,12221,22221,12221,22221,1111,
%U A291073 1211,2111,2211,1111,1211,2111,2211,1111,1211,2111,2211,1111,1211,2111
%N A291073 Take n-th string over {1,2} in lexicographic order and apply the Watanabe tag system {00, 1110} described in A291068 (but adapted to the alphabet {1,2}) just once.
%p A291073 See A291072.
%Y A291073 Cf. A007931, A284116, A291067, A291068, A291069.
%Y A291073 Cf. also A289673, A291072, A291074.
%K A291073 sign
%O A291073 1,2
%A A291073 _N. J. A. Sloane_, Aug 18 2017