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Search: id:A006534
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| A006534 |
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Number of one-sided triangular polyominoes (n-iamonds) with n cells (turning over not allowed) (holes are allowed).
(Formerly M3287)
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+0
6
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| 1, 1, 1, 4, 6, 19, 43, 120, 307, 866, 2336, 6588, 18373, 52119, 147700, 422016, 1207477, 3471067, 9999135, 28893560, 83665729, 242826187, 706074369, 2056870697, 6001555275, 17538335077, 51323792789, 150390053432
(list; graph; listen)
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OFFSET
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1,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
F. Harary, Graphical enumeration problems; in Graph Theory and Theoretical Physics, ed. F. Harary, Academic Press, London, 1967, pp. 1-41.
W. F. Lunnon, Counting hexagonal and triangular polyominoes, pp. 87-100 of R. C. Read, editor, Graph Theory and Computing. Academic Press, NY, 1972.
J. Meeus, personal communication.
P. J. Torbijn, Polyiamonds, J. Rec. Math., 2 (1969), 216-227.
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LINKS
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Ed Pegg, Jr., Illustrations of polyforms
R. K. Guy, O'Beirne's Hexiamond, in The Mathemagician and the Pied Puzzler - A Collection in Tribute to Martin Gardner, Ed. E. R. Berlekamp and T. Rogers, A. K. Peters, 1999, 85-96.
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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CROSSREFS
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Cf. A000577, A006534, A030223, A030224, A001420.
Sequence in context: A095383 A116383 A026521 this_sequence A064035 A010364 A110391
Adjacent sequences: A006531 A006532 A006533 this_sequence A006535 A006536 A006537
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KEYWORD
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nonn,hard,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Corrected and extended by David W. Wilson (davidwwilson(AT)comcast.net). a(19) from Achim Flammenkamp (achim(AT)uni-bielefeld.de) Feb 15 1999.
a(20) to a(28) from Joseph Myers (jsm(AT)polyomino.org.uk), Sep 24 2002
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