OFFSET
0,3
LINKS
Eric Weisstein's World of Mathematics, Permutation Pattern
Wikipedia, Permutation pattern
EXAMPLE
For n = 4, the valid permutations are the 20 which are not elements of the set {1234,1324,1342,2413}, hence a(4) = 20.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Matt Slattery-Holmes, Jan 23 2024
EXTENSIONS
a(13)-a(20) from Martin Ehrenstein, Feb 24 2024
STATUS
approved