Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:264AU5of8 GHM

Order: 20

Horizontal side: 264 Vertical side: 264

Elements: 8√2, 16, 20, 16√2, 32, 24√2, 32√2, 46, 33√2, 40√2, 46√2, 66, 72, 80, 86, 66√2, 112, 99√2, 152, 132√2.

Code: 1525 0 112 1324 132 132 996 165 165 330 165 165 201 152 132 462 198 86 461 198 132 662 264 66 1125 0 0 801 80 112 242 104 88 721 152 112 80 104 88 863 198 0 160 96 80 161 112 80 402 152 40 663 264 0 327 80 64 326 80 32

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)