Polyhex (mathematics)
In recreational mathematics, a polyhex is a polyform with a regular hexagon (or 'hex' for short) as the base form.
As with polyominoes, polyhexes may be enumerated as free polyhexes (where rotations and reflections count as the same shape), fixed polyhexes (where different orientations count as distinct) and one-sided polyhexes (where mirror images count as distinct but rotations count as identical). They may also be distinguished according to whether they may contain holes. The number of free -hexes for = 1, 2, 3, … is 1, 1, 3, 7, 22, 82, 333, 1448, … (sequence in the OEIS); the number of free polyhexes with holes is given by 
; the number of free polyhexes without holes is given by ; the number of fixed polyhexes is given by ; the number of one-sided polyhexes is given by .
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