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A338729
a(n) = number of permutations avoiding the simsum pattern 213 and the classical pattern 321.
0
1, 1, 2, 4, 8, 18, 45, 119
OFFSET
0,3
LINKS
Marilena Barnabei, Flavio Bonetti, Niccolò Castronuovo, Matteo Silimbani, Permutations avoiding a simsun pattern, The Electronic Journal of Combinatorics (2020) Vol. 27, Issue 3, P3.45. See Section 4.3.
CROSSREFS
Sequence in context: A125809 A245176 A000117 * A308030 A252653 A006771
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Dec 01 2020.
STATUS
approved