congruent prime
(another Prime Pages' Glossary entries)
The Prime Glossary
Glossary: Prime Pages: Top 5000:
GIMPS has discovered a new largest known prime number: 282589933-1 (24,862,048 digits)

A congruent prime contains "shapes" of identical digits nested about the center when drawn in the form of symmetrical figures and polygons. The original prime can be constructed by concatenating each row left-to-right, top-to-bottom, as oriented in the drawing. E.g., 111181111 is a square-congruent prime.

1 1 1
1 8 1 
1 1 1

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