Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:114AT GHM

Order: 20

Horizontal side: 114 Vertical side: 114

Elements: 2, 2√2, 3, 3√2, 6, 9, 9√2, 18, 22, 24, 26, 30, 22√2, 44, 46, 33√2, 48, 46√2, 66, 68.

Code: 685 0 46 661 66 114 332 99 81 481 114 114 36 96 78 65 99 75 303 96 48 35 96 75 97 96 75 90 105 75 187 96 66 443 114 22 24 68 46 23 70 46 267 70 48 467 0 46 460 46 46 241 70 46 224 92 0 223 114 0

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)