Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:88AQ GHM

Order: 20

Horizontal side: 88 Vertical side: 88

Elements: 4√2, 8, 8√2, 14, 11√2, 16, 13√2, 14√2, 22, 16√2, 17√2, 26, 19√2, 28, 32, 24√2, 34, 28√2, 32√2, 56.

Code: 567 0 88 320 56 88 321 88 88 246 0 32 265 24 30 221 46 56 147 46 56 146 46 42 287 60 56 286 60 28 85 46 34 44 50 30 176 37 17 345 54 0 162 16 16 112 35 19 134 37 17 190 35 19 163 16 0 82 24 8

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)