a grocer stacks oranges in a square pyramid. each orange sits on the 4 oranges below it. so, the top layer has 1 orange and the layer below it has 4 oranges. the layer below that has 9 oranges. the total number of oranges required for 1 layer is 1. the total number of oranges required for 2 layers is 5. the total number of oranges required for 3 layers is 14. Write a recursive formula for the sequence. how many oranges are required for 10 layers?