Explanation:
Let the number of stickers he used for first page be x.
By the question,
x + 1 + 2x + 2(1+2x) - 4 + 1 = 105
or, 3x + 2 + 4x = 105 - 2 + 4
or, 7x = 105
so, x = 15 (for first page)
For second page = 1 + 2x = 1 + 2*15 = 31 stickers
For third page = 2(1+2*15)-4 = 62 - 4 = 58 stickers