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 A194811 #19 Feb 19 2018 22:02:25 %S A194811 1,5,13,25,37,53,81,113,133,149,177,213,253,313,401,481,517,533,561, %T A194811 597,637,697,785,869,925,985,1077,1189,1329,1537,1793,1985,2053,2069, %U A194811 2097,2133,2173,2233,2321,2405,2461,2521,2613,2725,2865,3073,3329,3525,3613 %N A194811 Number of grid points that are covered after n-th stage of A139250 version "Tree", starting with a(0) = 1 and assuming the toothpicks have length 4, 3, and 2. %C A194811 The first differences give A147646. %H A194811 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> %H A194811 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %F A194811 a(n) = 1 + 4*A153006(n) = 1 + A159795(n). %Y A194811 Cf. A139250, A152980, A153006, A147646, A159795, A160128, A160420, A160422, A160425, A182618, A194800, A194802. %K A194811 nonn %O A194811 0,2 %A A194811 _Omar E. Pol_, Oct 24 2011