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 A092437 Triangle read by rows, arising from enumeration of domino tilings of Aztec Pillow-like regions. 6
 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; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS 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). REFERENCES 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). LINKS 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 CROSSREFS Cf. A092438-A092443. Sequence in context: A266681 A210664 A176093 * A064814 A051012 A064644 Adjacent sequences:  A092434 A092435 A092436 * A092438 A092439 A092440 KEYWORD hard,nonn,tabf AUTHOR Christopher Hanusa (chanusa(AT)math.washington.edu), Mar 24 2004 STATUS approved

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Last modified February 21 01:29 EST 2019. Contains 320364 sequences. (Running on oeis4.)