The first line: 1

Line 2: Line 3

Line 3: Line 5

. . . . . .

Line n: 2n- 1

Then, the number of small triangles in the largest regular triangle is n * n

And it is easy to find that black diamonds also conform to this law. Then we can assume that it has 2m rows of small regular triangles, and the total number should be 2 m * m.