|
|
A337522
|
|
Number of permutations of length n that are sorted to the identity by a consecutive-312-avoiding-stack followed by a classical-21-avoiding stack.
|
|
0
|
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
EXAMPLE
|
Sending the permutation 132 through a consecutive-312-avoiding stack results in 231, and a classical 21-avoiding stack then sends 231 to 213, which is not the identity 123. Applying this procedure to any permutation of length 3 other than 132 results in 123, so a(3)=5.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|