Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:100AB GHM

Order: 20

Horizontal side: 100 Vertical side: 100

Elements: 4√2, 5√2, 8, 6√2, 10, 8√2, 10√2, 15√2, 24, 28, 30, 24√2, 36, 26√2, 38, 28√2, 32√2, 48, 36√2, 38√2.

Code: 382 38 62 324 32 68 266 38 74 367 64 100 366 64 64 66 32 68 305 38 44 82 72 56 383 38 24 83 72 48 282 100 28 44 68 44 483 72 0 102 48 34 154 53 29 103 48 24 52 53 29 283 100 0 245 0 0 244 24 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)