Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:192BB2of4 GHM

Order: 20

Horizontal side: 192 Vertical side: 192

Elements: 1√2, 2, 2√2, 4, 3√2, 4√2, 5√2, 9√2, 14, 18, 32, 23√2, 46, 64, 46√2, 82, 64√2, 73√2, 128, 96√2.

Code: 1285 0 64 964 96 96 736 119 119 230 119 119 321 128 96 147 128 96 56 137 91 42 146 92 36 143 89 462 192 46 90 137 91 10 143 89 27 142 88 20 144 88 41 146 86 187 128 82 823 146 0 645 0 0 644 64 0 463 192 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)