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 A329776 a(n) = (1/n!)*Sum_{i=0..n-2} (4*(2*n+1)!*(2*n-i-4)!/(i!*(n-i-2)!*(2*n-i+1)). 1
 0, 48, 1520, 134640, 24438960, 7531426560, 3520642164480, 2320166170022400, 2048045044749580800, 2331685226745120153600, 3325737272677280068608000, 5807366064051899816012544000, 12184317992530053651613812480000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For n >= 3, this is related to the enumeration of rooted simple planar maps with n edges. See A329775 for another version. Presumably only one of the two versions is correct. REFERENCES Liu, Yanpei, On the enumeration of simple planar maps, RUTCOR Research Report #37-87, Nov. 1987, RUTCOR, Hill Center, Rutgers University, NJ. See (20). Liu, Yanpei, An enumerating equation of simple planar maps with face partition, RUTCOR Research Report #38-87, Nov. 1987, RUTCOR, Hill Center, Rutgers University, NJ. See (22). LINKS Yanpei Liu, On functional equations arising from map enumerations, Discrete Mathematics 123.1-3 (1993): 93-109. See (4.16). MAPLE f:=m -> (1/m!)*add(4*(2*m+1)!*(2*m-i-4)!/(i!*(m-i-2)!*(2*m-i+1)), i=0..m-2); [seq(f(m), m=1..40)]; CROSSREFS Cf. A329775. Sequence in context: A275042 A062195 A264322 * A266160 A004386 A076003 Adjacent sequences:  A329773 A329774 A329775 * A329777 A329778 A329779 KEYWORD nonn AUTHOR N. J. A. Sloane, Nov 25 2019 STATUS approved

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Last modified April 5 03:58 EDT 2020. Contains 333238 sequences. (Running on oeis4.)