WAztec diamond
WDe Bruijn sequence
WCatalan number
WDedekind number
WDouble factorial
WDyson conjecture
WEight queens puzzle
WFence (mathematics)
WGraph enumeration
WInclusion–exclusion principle
WLattice path
WNecklace (combinatorics)
WNoncrossing partition
WOrdered Bell number
WPlane partition
WSchröder–Hipparchus number
WSuperpermutation
WTelephone number (mathematics)