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 A297877 Triangle T(n,k) read by rows, giving number of bipartite graphs with n nodes (n >= 0) and k edges (0 <= k <= floor(n/2*n/2)). 2
 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 3, 4, 1, 1, 1, 1, 2, 4, 7, 8, 6, 3, 2, 1, 1, 1, 2, 4, 8, 13, 19, 14, 13, 7, 4, 1, 1, 1, 1, 2, 4, 9, 16, 32, 45, 52, 48, 40, 24, 16, 7, 3, 2, 1, 1, 1, 2, 4, 9, 17, 38, 70, 120, 150, 179, 164, 143, 94, 63, 32, 19, 7, 4, 1, 1, 1, 1, 2, 4, 9, 18, 41, 85, 181, 324, 500, 659 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,10 COMMENTS The sum of the m-th row is the (m-1)-st member of A033995, number of bipartite graphs with n nodes. REFERENCES F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, New York / London, 1973. LINKS P. Hanlon, The enumeration of bipartite graphs, Discrete Math. 28 (1979), 49-57. Juergen Will, Rows 0 to 10 of triangle. EXAMPLE Triangle begins: 0:  1; 1:  1; 2:  1,  1; 3:  1,  1,  1; 4:  1,  1,  2,  2,  1; 5:  1,  1,  2,  3,  4,  1,  1; 6:  1,  1,  2,  4,  7,  8,  6,  3,  2,  1; 7:  1,  1,  2,  4,  8, 13, 19, 14, 13,  7,  4,  1,  1; CROSSREFS Cf. A033995 (row sums). Sequence in context: A071127 A029381 A343558 * A027926 A114730 A031282 Adjacent sequences:  A297874 A297875 A297876 * A297878 A297879 A297880 KEYWORD nonn,tabf AUTHOR Juergen Will, Jan 07 2018 STATUS approved

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Last modified July 25 19:05 EDT 2021. Contains 346291 sequences. (Running on oeis4.)