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 A172306 #15 Apr 09 2021 15:50:19 %S A172306 0,1,3,7,11,15,23,31,35,43,55,67,83,95,119,139,151,159,171,191,215, %T A172306 235,263,291,323,355,391,419,451,475,515,559,575,591,623,659,691,711, %U A172306 743,783,831,883,955,1003,1067,1127,1207,1263,1311,1351,1415,1479,1551,1595,1663,1727,1795,1867,1951,2035,2143,2223,2319,2403,2435,2475,2539,2587 %N A172306 a(n) = A172304(n)/2. %H A172306 Robert Price, <a href="/A172306/b172306.txt">Table of n, a(n) for n = 0..202</a> %H A172306 David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.] %H A172306 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS"> Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %Y A172306 Cf. A139250, A172304, A172305, A172307, A172308, A172309, A172310, A172311, A172312, A172313. %K A172306 nonn %O A172306 0,3 %A A172306 _Omar E. Pol_, Feb 06 2010 %E A172306 a(14)-a(67) from _Robert Price_, Jun 17 2019