22222...22221 (100-digits)

This number is a prime.

                                            2222222222 2222222222 2222222222
2222222222 2222222222 2222222222 2222222222 2222222222 2222222222 2222222221

Just showing those entries submitted by 'Schiffman': (Click here to show all)

The one hundrdth term in the almost repunit sequence 1, 21, 221, 2221, 22221, ..., is the prime. This sequence can be defined by the recursion rule a(1) = 1 and a(n) = 10 * a(n - 1) + 11 for n > 1. [Schiffman]