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 A245549 #22 Feb 16 2025 08:33:23
%S A245549 1,111,11001,1101111,110010001,11011110111,1100100001001,
%T A245549 110111100111111,11001000111000001,1101111011001000111,
%U A245549 110010000101111011001,11011110011010000101111
%N A245549 State of one-dimensional cellular automaton 'sigma' (Rule 30): 000,001,010,011,100,101,110,111 -> 0,0,0,1,1,1,1,0 at generation n, regarded as a binary number.
%C A245549 See A110240 for decimal equivalents. See A070952 for number of ON cells.
%H A245549 Robert Price, <a href="/A245549/b245549.txt">Table of n, a(n) for n = 0..999</a>
%H A245549 N. J. A. Sloane, <a href="/A070952/a070952.png">Illustration of first 20 generations</a>
%H A245549 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Rule150.html">Rule 150</a>
%H A245549 S. Wolfram, <a href="http://wolframscience.com/">A New Kind of Science</a>
%H A245549 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%H A245549 <a href="https://oeis.org/wiki/Index_to_Elementary_Cellular_Automata">Index to Elementary Cellular Automata</a>
%t A245549 rule=30; rows=20; ca=CellularAutomaton[rule, {{1}, 0}, rows-1, {All, All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]], {rows-k+1, rows+k-1}], {k, 1, rows}]; (* Truncated list of each row *) Table[FromDigits[catri[[k]]], {k, 1, rows}] (* Binary Representation of Rows *)(* _Robert Price_, Feb 21 2016 *)
%Y A245549 Cf. A070952, A110240, A070950, A074890, A269160.
%K A245549 nonn
%O A245549 0,2
%A A245549 _N. J. A. Sloane_, Jul 28 2014