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 A189507 Triangle read by rows: T(n,k) (n >= 0, 1 <= k <= n+1) are the signed Hultman numbers. 7
 1, 1, 1, 4, 3, 1, 20, 21, 6, 1, 148, 160, 65, 10, 1, 1348, 1620, 701, 155, 15, 1, 15104, 19068, 9324, 2247, 315, 21, 1, 198144, 264420, 138016, 38029, 5908, 574, 28, 1, 2998656, 4166880, 2325740, 692088, 124029, 13524, 966, 36, 1, 51290496, 74011488, 43448940, 13945700, 2723469, 344961, 27930, 1530, 45, 1, 979732224, 1459381440, 897020784, 305142068, 64711856, 8996295, 850905, 53262, 2310, 55 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS "Signed" refers to the fact that these numbers are associated with signed permutations. The numbers themselves are positive. LINKS N. Alexeev, A. Pologova, M. A. Alekseyev, Generalized Hultman Numbers and Cycle Structures of Breakpoint Graphs, Journal of Computational Biology 24:2 (2017), 93-105. doi:10.1089/cmb.2016.0190 arXiv:1503.05285 Simona Grusea and Anthony Labarre, The distribution of cycles in breakpoint graphs of signed permutations, arXiv:1104.3353v1 EXAMPLE Triangle begins: 1 1 1 4 3 1 20 21 6 1 148 160 65 10 1 1348 1620 701 155 15 1 15104 19068 9324 2247 315 21 1 ... CROSSREFS The first three columns give A001171, A189508, A189509. Cf. A164652. Sequence in context: A193795 A181355 A128320 * A208057 A298673 A245732 Adjacent sequences:  A189504 A189505 A189506 * A189508 A189509 A189510 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Apr 23 2011 STATUS approved

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Last modified June 15 20:50 EDT 2019. Contains 324145 sequences. (Running on oeis4.)