Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:294AG GHM

Order: 20

Horizontal side: 294 Vertical side: 294

Elements: 2, 2√2, 4, 6, 6√2, 10, 12, 34, 34√2, 68, 61√2, 63√2, 90, 68√2, 102, 90√2, 136, 102√2, 170, 192.

Code: 1927 0 294 680 192 294 681 260 294 342 294 260 341 294 294 1703 294 90 636 61 163 1367 124 226 610 61 163 1027 0 102 1020 102 102 121 114 102 62 120 96 61 120 102 27 120 102 20 122 102 47 120 100 103 124 90 904 204 0 903 294 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)