Primitive Perfect Isosceles Right Triangled Square

Title: __ 18:184AT GHM

Order: 18

Horizontal side: 184 Vertical side: 184

Elements: 1√2, 2, 4, 4√2, 8, 8√2, 16, 14√2, 16√2, 32, 30√2, 62, 46√2, 61√2, 62√2, 92, 122, 92√2.

Code: 1225 0 62 924 92 92 923 184 92 304 122 62 166 136 76 327 152 92 466 138 46 86 128 68 165 136 60 46 124 64 85 128 60 23 124 62 45 124 60 625 0 0 624 62 0 16 123 61 610 123 61 144 138 46

The properties below may precede order:side in a tiling's title:

• c = crossed. There is a tile-corner traversed by two lines. The only known crossed PPIRTS's below order 20 are 19:35AB1of4 and 19:35AB4of4.
• d = double-pentagon patterned. Every such tiling is a subdivision of an instance of the same deformable tiling by two 45-90-90-90-225 pentagons with a shared side, four triangles and two pseudotriangles. All below order 19 are degenerate in the sense that one or more sides of underlying tiles have shrunk to zero length. The non-degenerate d-tilings of order 19 are 19:221AA, 19:229AB and 19:241AA.
• e = elegant. No tile-corner is just a T-junction. Such tilings may be considered aesthetically pleasing. The only known elegant PPIRTS's below order 16 are 13:21AA, 14:26AJ, 14:35AA and 15:55AA.
• i = isomers exist which are ineligible for this catalogue. They are not included in the isomer count which follows 'of' in the tiling id.
• r = rectangular inclusion. The only known PPIRTS's below order 16 with a rectangular inclusion are 13:18AA1-4of4 and 15:44AA1-4of4.

Credit for Discovery

Just three people are credited with the discovery of Primitive Perfects:

Geoffrey H. Morley (GHM, England)

Jasper D. Skinner, II (JDS, United States)

William T. Tutte (WTT, Canada, 1917-2002) (15:44AI, 17:136AJ and 19:56AJ only)