OFFSET
0,3
COMMENTS
Conjecture: The number of Dumont permutations of the first kind avoiding pattern 2143 equals the number of Dumont permutations of the first kind avoiding pattern 3421 for all n >= 0.
Data for n=7,8,9,10 is due to Michael Albert.
REFERENCES
O. Jones, Enumeration of Dumont permutations avoiding certain four-letter patterns, Ph.D. thesis, Howard University, 2019.
LINKS
D. Dumont, Interprétations combinatoires des nombres de Genocchi, Duke Math. J., 41 (1974), 305-318.
EXAMPLE
For n=3, the 7 Dumont permutations of the first kind avoiding pattern 2143 are 356421, 364215, 435621, 563421, 564213, 634215, 642135, and the 7 Dumont permutations of the first kind avoiding pattern 3421 are 214365, 216435, 421365, 421563, 421635, 621435, 642135.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Alexander Burstein and Opel Jones, Jun 21 2019
STATUS
approved