The first six rows of Pascal's triangle are shown below, beginning with row zero. Except for the 1 at each end, row 4 consists of only even numbers, as does row 2 .How many of the first 20 rows have this property? (Don't include row 0 or row 1).
Among the first 20 rows, there are 10 rows that have this property.
The EVEN rows are all powers of 2 as follows:
2^1 , 2^2, 2^3, 2^4 ==2nd row, 4th row, 8th row, 16th row ==4 rows < 20