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 A056842 Number of polydrafters: a(n) is the number of polydrafters with n cells. 5
 1, 6, 14, 64, 237, 1024, 4254, 18664, 81865, 365190, 1634801, 7388372 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See the Paterson link for the definition. Restatement of the definition: A polydrafter is a polygon formed by joining 30-60-90 triangles, according to the following rules: (a) Two triangles may be joined along their short legs, with their right angles touching; (b) Two triangles may be joined along their long legs, with their right angles touching; (c) Two triangles may be joined along their hypotenuses, in either direction; (d) The short leg of triangle 1 may be joined to half of the hypotenuse of triangle 2, with the right angle of triangle 1 touching the midpoint of the hypotenuse of triangle 2. REFERENCES Ed Pegg, Jr., Polyform puzzles, in Tribute to a Mathemagician, Peters, 2005, pp. 119-125. LINKS Table of n, a(n) for n=1..12. D. Paterson, Pentominos & Dodecadudes M. Vicher, Polyforms M. Vicher, Tridrafters Eric Weisstein's World of Mathematics, Polydrafter. EXAMPLE a(3) = 14 because there are 14 tridafters. The second Vicher link shows various arrangements of them. CROSSREFS Cf. A217720 (number of one-sided polydrafters with n cells). Cf. A289137 (number of extended [two-sided] polydrafters with n cells). Sequence in context: A252541 A333103 A139257 * A182752 A200033 A219376 Adjacent sequences: A056839 A056840 A056841 * A056843 A056844 A056845 KEYWORD nonn,more,hard AUTHOR James A. Sellers, Aug 28 2000 EXTENSIONS Edited by David Wasserman, Dec 01 2003 a(10) from George Sicherman, Jun 23 2020 a(11)-a(12) from Aaron N. Siegel, May 13 2022 STATUS approved

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Last modified September 23 00:10 EDT 2023. Contains 365532 sequences. (Running on oeis4.)