Two patterns and belong to the same Wilf class if for all , where denotes the set of permutations on that avoid the pattern . Two sets having the same Wilf class are said to be Wilf equivalent.

# Wilf Class

## See also

Avoided Pattern, Wilf Equivalent, Permutation Pattern## Explore with Wolfram|Alpha

## References

Mansour, T. "Permutations Avoiding a Pattern from and at Least Two Patterns from ." 31 Jul 2000. http://arxiv.org/abs/math.CO/0007194.## Referenced on Wolfram|Alpha

Wilf Class## Cite this as:

Weisstein, Eric W. "Wilf Class." From
*MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/WilfClass.html