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 A299705 #23 Feb 23 2018 11:25:21 %S A299705 1,0,0,1,0,1,2,3,9,23,62,188,574,1826,5953,19664,66049,224700,771859, %T A299705 2674753 %N A299705 Number of ways to dissect an equilateral triangle into n non-overlapping equilateral triangles counting isomorphisms only once. %C A299705 Data from Figure 7 of Drapal and Hamalainen, see link. %H A299705 Ales Drapal, Carlo Hamalainen, <a href="http://arxiv.org/abs/0910.5199">An enumeration of equilateral triangle dissections</a>, arXiv:0910.5199 [math.CO], 2009-2010. %H A299705 Hugo Pfoertner, Rainer Rosenthal, <a href="/A299705/a299705.txt">Illustration of the 23 dissections into 10 triangles.</a> %e A299705 a(9)=9: %e A299705 * * * %e A299705 / \ / \ / \ %e A299705 *---* + + + + %e A299705 / \ / \ / \ / \ %e A299705 *---*---* + + + + %e A299705 / \ / \ / \ / \ / \ %e A299705 *---*---*---* + + + + %e A299705 / \ / \ %e A299705 *---+---*---+---* *---+---+---*---* %e A299705 / \ / \ / \ / \ / \ / \ %e A299705 + + + + + + + + *---*---* %e A299705 / \ / \ / \ / \ / \ / \ %e A299705 + *---*---* + + + + + + + %e A299705 / \ / \ / \ / \ / \ / \ %e A299705 *---+---+---*---*---+---+---* *---+---+---*---+---*---+---* %e A299705 . %e A299705 * *---+---+---*---+---+---* * %e A299705 / \ \ / \ / / \ %e A299705 + + + + + + + + %e A299705 / \ \ / \ / / \ %e A299705 + + + *---*---* + + + %e A299705 / \ \ / \ / \ / \ / / \ %e A299705 + + *---*---*---* + + %e A299705 / \ \ / / \ %e A299705 *---+---*---+---* + + *---+---*---*---* %e A299705 / \ / \ / \ \ / / \ / \ / \ / \ %e A299705 + + + + *---* + + + + + *---* + %e A299705 / \ / \ / \ / \ \ / / \ / \ / \ %e A299705 *---+---*---+---*---*---* * *---+---*---+---*---+---* %e A299705 . %e A299705 * *---+---*---*---*---+---* * %e A299705 / \ \ / \ / \ / \ / / \ %e A299705 + + + + *---* + + + + %e A299705 / \ \ / \ / \ / / \ %e A299705 *---*---* *---+---*---+---* + + %e A299705 / \ / \ / \ \ / / \ %e A299705 *---*---*---* + + *---+---+---* %e A299705 / \ / \ \ / / \ / \ %e A299705 + + + + + + + + + + %e A299705 / \ / \ \ / / \ / \ %e A299705 + + + + + + *---*---* + + %e A299705 / \ / \ \ / / \ / \ / \ / \ %e A299705 *---+---+---*---+---+---* * *---*---*---*---+---+---* %Y A299705 Cf. A167123, A290697, A290821. %K A299705 nonn,hard,more %O A299705 1,7 %A A299705 _Peter Munn_ and _Hugo Pfoertner_, Feb 17 2018 %E A299705 Offset changed, also name to accommodate, following suggestion by _M. F. Hasler_, Feb 23 2018