Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:192BA GHM

Order: 20

Horizontal side: 192 Vertical side: 192

Elements: 5√2, 10, 12, 10√2, 12√2, 15√2, 24, 30, 24√2, 28√2, 50, 56, 40√2, 68, 50√2, 56√2, 80, 68√2, 112, 124.

Code: 1245 0 68 1121 112 192 502 162 142 801 192 192 503 162 92 305 162 112 102 172 102 154 177 97 566 136 56 103 172 92 52 177 97 127 112 92 126 112 80 245 124 68 244 148 68 687 0 68 680 68 68 404 108 28 286 108 28 565 136 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)