44444...44443 (32-digits)

This number is a prime.

                                         44 4444444444 4444444444 4444444443

The largest prime output among the initial one hundred terms in the almost repunit sequence 3, 43, 443, 4443, 44443, etc. The closed formula for this sequence is given by u (n) = (4 * 10 ^ n - 13) / 9 and a recursive formula is given as follows: Define u (1) = 3 and u (n) = 10 * u (n - 1) + 13 for n > 1. [Schiffman]