|
|
A125660
|
|
Number of 3-noncrossing tangled-diagrams.
|
|
0
|
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
D_{2,k}(n) = Sum_{i=0..n} binomial(n,i) * T_{2,k} (n-i), where T_{2,k}(n) = Sum_{L=0..n} binomial(n,L) * f_k(2n-L), and f_k(2n-L) is the number of k-noncrossing matchings over 2n-L vertices. [edited, using formulas from p. 12 of the paper by Chen et al., by Jon E. Schoenfield, Jul 21 2019]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
Jing Qin (qj(AT)cfc.nankai.edu.cn), Oct 26 2007
|
|
STATUS
|
approved
|
|
|
|