cp's OEIS Frontend

A006074 Number of polyaboloes (or polytans): number of different shapes that can be formed with n congruent isosceles right triangles, identifying mirror images.

%I A006074 M2379 #64 Feb 16 2025 08:32:29
%S A006074 1,3,4,14,30,107,318,1116,3743,13240,46476,166358,596638,2158829,
%T A006074 7839845,28616815,104814161,385269397,1420242629,5249877583,
%U A006074 19452536934,72237904034
%N A006074 Number of polyaboloes (or polytans): number of different shapes that can be formed with n congruent isosceles right triangles, identifying mirror images.
%C A006074 Also called supertangrams: a generalization of tangrams.
%D A006074 Martin Gardner, Mathematical Magic Show. Random House, NY, 1978, p. 151 (but beware errors).
%D A006074 T. H. O'Beirne, New Scientist, 266 (Dec 21 1961), p. 752.
%D A006074 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006074 Ed Pegg, Jr., <a href="http://demonstrations.wolfram.com/PolyformExplorer/">Illustrations of polyforms</a>
%H A006074 Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/Polyaboloes.htm">Polyaboloes</a>
%H A006074 Andrew Clarke, <a href="/A006074/a006074.gif">Illustration of initial terms</a>
%H A006074 Michael Keller, <a href="http://www.solitairelaboratory.com/polyenum.html">Counting Polyforms</a>
%H A006074 Henri Picciotto, <a href="http://www.mathedpage.org/puzzles/#supertangrams">Geometric Puzzles</a>
%H A006074 Miroslav Vicher, <a href="http://www.vicher.cz/puzzle/polyforms.htm">Polyforms</a>
%H A006074 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyabolo.html">Polyabolo</a>
%H A006074 Wikimedia, <a href="https://en.wikipedia.org/wiki/Polyabolo">Polyabolo</a>
%Y A006074 Cf. A151519 (distinguishing mirror images), A245676 (number of convex polyaboloes). - _George Sicherman_, Nov 25 2017
%K A006074 nonn,nice,hard,more
%O A006074 1,2
%A A006074 _N. J. A. Sloane_
%E A006074 Corrected values for a(8) and a(9), found by _Aaron N. Siegel_ and confirmed by a Japanese puzzlist named Taro, reported by Michael Keller (Wgreview(AT)aol.com), Sep 02 2000
%E A006074 One more term from _Vladeta Jovovic_, Aug 11 2007
%E A006074 Link updated by _William Rex Marshall_, Dec 16 2009
%E A006074 Modified the definition (what is a "half-square"?) and added a(13), by _George Sicherman_, Apr 04 2012
%E A006074 a(14) from _Juris Cernenoks_, Sep 06 2012
%E A006074 a(15) from _George Sicherman_, Aug 02 2013
%E A006074 a(16)-a(20) from _John Mason_, Jan 07 2022
%E A006074 a(21) from _Aaron N. Siegel_, May 17 2022
%E A006074 a(22) from _Aaron N. Siegel_, Jun 07 2022