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 A123850 Triangle read by rows: T(n,k) = orientable embedding number gamma_k for bouquet B_n, n >= 0, 0 <= k <= [n/2]. 1
 1, 1, 4, 2, 40, 80, 672, 3360, 1008, 16128, 161280, 185472 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES Jonathan L. Gross and Thomas W. Tucker, Enumerating graph embeddings and partial-duals by genus and Euler genus, ECA 1:1 (2021) Article S2S1. See Table 1. (Beware errors!) J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 649. LINKS Table of n, a(n) for n=0..11. FORMULA Reference gives a recurrence. EXAMPLE Triangle begins: 1 1 4 2 40 80 672 3360 1008 16128 161280 185472 CROSSREFS Columns give A005431, A123828. Row sums are (2n-1)1. Sequence in context: A302890 A307974 A303625 * A280780 A264755 A120968 Adjacent sequences: A123847 A123848 A123849 * A123851 A123852 A123853 KEYWORD nonn,tabf,more AUTHOR N. J. A. Sloane, Nov 19 2006 STATUS approved

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Last modified July 14 03:51 EDT 2024. Contains 374291 sequences. (Running on oeis4.)