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 A170889 #11 Feb 24 2021 02:48:19 %S A170889 0,1,2,4,4,4,6,10,8,4,6,10,10,12,20,26,16,4,6,10,10,12,20,26,18,12,20, %T A170889 28,30,42,64,66,32,4,6,10,10,12,20,26,18,12,20,28,30,42,64,66,34,12, %U A170889 20,28,30,42,64,68,46,42,66,84,100,146,192,162,64,4,6,10,10,12,20,26,18,12 %N A170889 First differences of toothpick sequence A170888. %H A170889 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 A170889 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> %e A170889 From _Omar E. Pol_, Jan 30 2013 (Start): %e A170889 Written as an irregular triangle: %e A170889 0; %e A170889 1; %e A170889 2; %e A170889 4,4; %e A170889 4,6,10,8; %e A170889 4,6,10,10,12,20,26,16; %e A170889 4,6,10,10,12,20,26,18,12,20,28,30,42,64,66,32; %e A170889 4,6,10,10,12,20,26,18,12,20,28,30,42,64,66,34,12,20,28,30,42,64,68,46,42,66,84,100,146,192,162,64; %e A170889 (End) %Y A170889 Cf. A139250, A139251, A160407, A170887, A170888, A170891, A170893. %K A170889 nonn,tabf %O A170889 0,3 %A A170889 _Omar E. Pol_, Jan 09 2010 %E A170889 Terms beyond a(10) from _R. J. Mathar_, Jan 25 2010