login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 (list; graph; refs; listen; history; text; internal format)
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
Andrew Clarke, Polyaboloes
Michael Keller, Counting Polyforms
Henri Picciotto, Geometric Puzzles
Miroslav Vicher, Polyforms
Eric Weisstein's World of Mathematics, Polyabolo
Wikimedia, Polyabolo
CROSSREFS
Cf. A151519 (distinguishing mirror images), A245676 (number of convex polyaboloes). - George Sicherman, Nov 25 2017
Sequence in context: A110565 A332270 A057433 * A081714 A117718 A268700
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
One more term from Vladeta Jovovic, Aug 11 2007
Link updated by William Rex Marshall, Dec 16 2009
Modified the definition (what is a "half-square"?) and added a(13), by George Sicherman, Apr 04 2012
a(14) from Juris Cernenoks, Sep 06 2012
a(15) from George Sicherman, Aug 02 2013
a(16)-a(20) from John Mason, Jan 07 2022
a(21) from Aaron N. Siegel, May 17 2022
a(22) from Aaron N. Siegel, Jun 07 2022
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 13 17:26 EDT 2024. Contains 371644 sequences. (Running on oeis4.)