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 A110000 #27 Sep 01 2023 11:18:32 %S A110000 1,4,6,5,8,7,8,7 %N A110000 Minimal number of polygonal pieces in a dissection of a regular n-gon to an equilateral triangle (conjectured). %C A110000 I do not know which of these values have been proved to be minimal. %C A110000 Turning over is allowed. The pieces must be bounded by simple curves to avoid difficulties with non-measurable sets. %D A110000 G. N. Frederickson, Dissections: Plane and Fancy, Cambridge, 1997. %D A110000 H. Lindgren, Geometric Dissections, Van Nostrand, Princeton, 1964. %D A110000 H. Lindgren (revised by G. N. Frederickson), Recreational Problems in Geometric Dissections and How to Solve Them, Dover, NY, 1972. %H A110000 Stewart T. Coffin, <a href="/A110312/a110312_3.gif">Dudeney's 1902 4-piece dissection of a triangle to a square</a>, from The Puzzling World of Polyhedral Dissections. %H A110000 Stewart T. Coffin, <a href="https://johnrausch.com/PuzzlingWorld/chap01.htm#p5">The Puzzling World of Polyhedral Dissections</a>, Chapter 1. (See section "Geometrical Dissections".) %H A110000 Geometry Junkyard, <a href="http://www.ics.uci.edu/~eppstein/junkyard/dissect.html">Dissection</a> %H A110000 Gavin Theobald, <a href="http://www.gavin-theobald.uk/HTML/Triangle.html">Triangle dissections</a> %H A110000 Vinay Vaishampayan, <a href="/A110312/a110312_3v.jpg">Dudeney's 1902 4-piece dissection of a triangle to a square</a> %e A110000 a(3) = 1 trivially. %e A110000 a(4) <= 4 because there is a 4-piece dissection of an equilateral triangle into a square, due probably to H. Dudeney, 1902 (or possible C. W. McElroy - see Fredricksen, 1997, pp. 136-137). Surely it is known that this is minimal? See illustrations. %e A110000 Coffin gives a nice description of this dissection. He notes that the points marked * are the midpoints of their respective edges and that ABC is an equilateral triangle. Suppose the square has side 1, so the triangle has side 2/3^(1/4). Locate B on the square by measuring 1/3^(1/4) from A, after which the rest is obvious. %e A110000 For n >= 5 see the Theobald web site. %Y A110000 Cf. A110312, A110356. %K A110000 nonn %O A110000 3,2 %A A110000 _N. J. A. Sloane_, Sep 11 2005