ARSE

Sat 23 Jan 2021

Centred Triangular Prime Days

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A centred triangular prime is a centred triangular number that is prime.

Centred triangular numbers are of the form
**(3n ^{2} + 3n + 2) / 2**

A centred triangular number is a centred figurate number that represents a triangle with a dot in the centre and all other dots surrounding the centre in successive triangular layers.

The figures for the first four centred triangular numbers are shown below: