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Search: id:A092437
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| A092437 |
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Triangle read by rows, arising from enumeration of domino tilings of Aztec Pillow-like regions. |
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7
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| 1, 1, 1, 2, 1, 1, 5, 6, 6, 1, 1, 5, 13, 26, 30, 20, 1, 1, 5, 13, 41, 90, 140, 140, 70, 1, 1, 5, 13, 41, 121, 302, 560, 742, 630, 252
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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The rows are of lengths 1, 3, 5, 7, ...
In particular, the rows are 1; 1,1,2; 1,1,5,6,6; 1,1,5,13,26,30,20; ... etc.
Call the first row row 0 and entries starting from 0. Then entries i=0 through k in row k are A046717(i).
In row k, entry k+1 is sequence A092438 and entry k+2 is sequence A092439.
In row k, entry 2k-1 is A002457(k-1) and entry 2k is A000984(k).
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REFERENCES
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J. Propp, Enumeration of matchings: problems and progress, pp. 255-291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 13).
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LINKS
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J. Propp, Publications and Preprints
J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics
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CROSSREFS
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Cf. A092438-A092443.
Sequence in context: A086856 A052916 A156576 this_sequence A064814 A051012 A064644
Adjacent sequences: A092434 A092435 A092436 this_sequence A092438 A092439 A092440
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KEYWORD
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hard,nonn,tabf
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AUTHOR
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Christopher Hanusa (chanusa(AT)math.washington.edu), Mar 24 2004
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