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 A171173 #11 Sep 26 2015 01:17:10
%S A171173 2,1,4,1,2,3,7,1,2,3,4,5,10,1,2,3,4,5,6,7,13,1,2,3,4,5,6,7,8,9,16,1,2,
%T A171173 3,4,5,6,7,8,9,10,11,19,1,2,3,4,5,6,7,8,9,10,11,12,13,22,1,2,3,4,5,6,
%U A171173 7,8,9,10,11,12,13,14,15,25,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,28,1
%N A171173 Triangle read by rows in which row n lists A033627(n) together with the first 2n-1 positive integers.
%C A171173 The same as A171172 except the initial term.
%C A171173 Also, a(n) is the length of each component of the n-th L-toothpick added to the structure of A171165.
%C A171173 See also A171175, a permutation of the natural numbers.
%H A171173 Harvey P. Dale, <a href="/A171173/b171173.txt">Table of n, a(n) for n = 1..10000</a>
%H A171173 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 A171173 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a>
%e A171173 Triangle begins:
%e A171173 2,1,
%e A171173 4,1,2,3,
%e A171173 7,1,2,3,4,5,
%e A171173 10,1,2,3,4,5,6,7,
%e A171173 13,1,2,3,4,5,6,7,8,9,
%e A171173 16,1,2,3,4,5,6,7,8,9,10,11,
%e A171173 19,1,2,3,4,5,6,7,8,9,10,11,12,13,
%e A171173 22,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,
%e A171173 25,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,
%t A171173 Join[{2,1},Flatten[Table[Flatten[{3n+1,Range[2n+1]}],{n,10}]]] (* _Harvey P. Dale_, Nov 24 2011 *)
%Y A171173 Cf. A000027, A033627, A172310, A171164, A161165, A161166, A171172, A171174, A171175, A171176, A171177, A171178.
%K A171173 easy,nonn,tabf
%O A171173 1,1
%A A171173 _Omar E. Pol_, Feb 23 2010