A331882 a(n) is the number of digits in the decimal expansion of the fractional part of Pi needed to contain n occurrences of an n-digit substring.
1, 22, 219, 1805, 25499, 168882, 3566679, 29325629
Offset: 1
Examples
a(1) = 1, because we need 1 digit to have the first 1-digit substring ('1') appearing 1 time;
a(2) = 22, because we need 22 digits (1415926535897932384626) to have the first 2-digit substring ('26') appearing 2 times;
a(3) is 219, because we need 219 digits (1415....933446) to have the first 3-digit substring ('446') appearing 3 times;
and so on.