A382139 Number of matchings of [2n] with no coupled arcs.
1, 1, 1, 9, 81, 705, 7665, 100905, 1524705, 26022465, 496042785, 10445342985, 240779831985, 6030718158465, 163087008669585, 4735950860666025, 146987669673669825, 4855606200012593025, 170101350767940617025, 6298861062893921346825, 245834199405298416337425
Offset: 0
Keywords
Links
- Sergi Elizalde and Emeric Deutsch, The degree of asymmetry of a sequence, Enum. Combinat. Applic. 2 (2022) no 1 #S2R7, eq (17) at r=1, s=2.
Programs
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Maple
g:= exp(-x^2)/sqrt(1-2*x) ; seq( coeftayl(g,x=0,n)*n!,n=0..10) ;