

A006074


Number of polyaboloes (or polytans): number of different shapes that can be formed with n congruent isosceles right triangles, identifying mirror images.
(Formerly M2379)


15



1, 3, 4, 14, 30, 107, 318, 1116, 3743, 13240, 46476, 166358, 596638, 2158829, 7839845, 28616815, 104814161, 385269397, 1420242629, 5249877583, 19452536934, 72237904034
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OFFSET

1,2


COMMENTS

Also called supertangrams: a generalization of tangrams.


REFERENCES

Martin Gardner, Mathematical Magic Show. Random House, NY, 1978, p. 151 (but beware errors).
T. H. O'Beirne, New Scientist, 266 (Dec 21 1961), p. 752.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Eric Weisstein's World of Mathematics, Polyabolo


CROSSREFS



KEYWORD

nonn,nice,hard,more


AUTHOR



EXTENSIONS

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
Modified the definition (what is a "halfsquare"?) and added a(13), by George Sicherman, Apr 04 2012


STATUS

approved



