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 A006978 M2642 #40 Jul 08 2025 16:58:19
%S A006978 1,3,7,13,31,49,115,215,509,775,1805,3359,7985,12659,29655,54909,
%T A006978 130759,197581,460383,855793,2038675,3227319,7562237,14149127,
%U A006978 33304077,50625055,118279729,220060275,523730647,830325757,1942439431,3595423245,8571017759,12951092785
%N A006978 Successive states of the Rule 110 cellular automaton defined by 000, 001, 010, 011, ..., 111 -> 0,1,1,1,0,1,1,0 when started with a single ON cell.
%D A006978 Marc LeBrun, personal communication.
%D A006978 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006978 Paolo Xausa, <a href="/A006978/b006978.txt">Table of n, a(n) for n = 1..1000</a>
%H A006978 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Rule110.html">Rule 110</a>
%H A006978 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%F A006978 a(n) = A117999(n-1)/2^(n-1). - _Pontus von Brömssen_, Oct 18 2022
%t A006978 Map[FromDigits[#, 2] &, CellularAutomaton[110, {{1}, 0}, 30]] (* _Ben Branman_, Dec 28 2010 *)
%Y A006978 Cf. A070887, A117999.
%K A006978 nonn
%O A006978 1,2
%A A006978 _N. J. A. Sloane_
%E A006978 More terms from _Eric W. Weisstein_, Apr 11 2006
%E A006978 Definition clarified by _N. J. A. Sloane_, Oct 18 2022