First find the total number of legos on the bottom layer: 7 legos * 7 legos = <<7*7=49>>49 legos
Then find the number of legos per side on the next layer: 7 legos - 1 lego = <<7-1=6>>6 legos
Then find the total number of legos on the second level: 6 legos * 6 legos = <<6*6=36>>36 legos
Then find the number of legos per side on the top level: 6 legos - 1 lego = <<6-1=5>>5 legos
Then find the total number of legos on the top level: 5 legos * 5 legos = <<5*5=25>>25 legos
Then add the number of legos on each level to find the total number of legos: 49 legos + 36 legos + 25 legos = <<49+36+25=110>>110 legos
#### 110