Here's a pretty (decimal) PrP, even if the "circle" is trivial: 11111111111111111111111111111111111111111111111111111111111 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000100000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 10000000000000000000000000000000000000000000000000000000001 11111111111111111111111111111111111111111111111111111111111 (33 rows by 59 columns with the extra "1" in the exact centre to save you counting.) Note: Entirely hollow rectangles are always divisible by 3 or 11. Andy