Primitive Perfect Isosceles Right Triangled Square

Title: __ 19:208BA GHM

Order: 19

Horizontal side: 208 Vertical side: 208

Elements: 2, 2√2, 4, 4√2, 7, 8, 8√2, 14√2, 15√2, 23, 30, 37√2, 52√2, 74, 67√2, 104, 74√2, 134, 104√2.

Code: 1345 0 74 1044 104 104 1043 208 104 301 134 104 142 148 90 374 171 67 526 156 52 86 140 82 235 148 67 46 136 78 85 140 74 26 134 76 45 136 74 25 134 74 745 0 0 744 74 0 73 148 67 670 141 67 154 156 52

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)