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 A170926 #18 Feb 24 2021 02:48:19 %S A170926 0,0,1,3,4,5,10,17,20,21,25,30,33,40,58,77,84,85,89,94,97,104,121,138, %T A170926 145,151,164,177,190,222,278,325,340,341,345,350,353,360,377,394,401, %U A170926 407,420,433,446,478,533,578,593,599,612,625,638,669,720,761,781,806,845,884,942 %N A170926 Total number of squares and rectangles at the n-th stage in the corner toothpick structure (see A152890, A153006). %H A170926 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 A170926 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> %F A170926 a(2^k) = (4^k-4)/3 for k >= 2. - _N. J. A. Sloane_, Feb 13 2010. %Y A170926 Partial sums of A168131. %K A170926 nonn %O A170926 0,4 %A A170926 _Omar E. Pol_, Jan 18 2010 %E A170926 Edited and extended by _N. J. A. Sloane_, Feb 01 2010