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A329775 a(1)=1, a(2)=2; thereafter a(n) = (1/n!)*Sum_{i=0..floor(n/2)} 4*(2*n+1)!*(2*n-i-4)!/(i!*(n-i-2)!*(2*n-i+1)). 1
1, 2, 1520, 134640, 24272640, 7527582720, 3517707916800, 2320039459584000, 2047894341292800000, 2331675471496250880000, 3325719719034680647680000, 5807364536076078278983680000, 12184314075622103163420672000000 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Related to the enumeration of rooted simple planar maps with n edges.
See A329776 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
f2:=n -> (1/n!)*add(4*(2*n+1)!*(2*n-i-4)!/(i!*(n-i-2)!*(2*n-i+1)), i=0..floor(n/2));
[1, 2, seq(f2(m), m=3..10)];
CROSSREFS
Cf. A329776.
Sequence in context: A319329 A058423 A233906 * A226699 A110027 A179866
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 25 2019
STATUS
approved

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Last modified July 24 21:09 EDT 2024. Contains 374585 sequences. (Running on oeis4.)