Primitive Perfect Isosceles Right Triangled Square

Title: __ 18:150AE GHM

Order: 18

Horizontal side: 150 Vertical side: 150

Elements: 12√2, 14√2, 24, 26, 30, 26√2, 27√2, 30√2, 32√2, 52, 54, 39√2, 58, 60, 64, 46√2, 66, 60√2.

Code: 667 0 150 396 27 111 267 66 150 260 92 150 581 150 150 527 66 124 643 118 60 322 150 92 270 27 111 466 104 46 547 0 84 243 54 60 122 66 72 306 0 30 607 30 60 600 90 60 144 104 46 305 0 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)