Question

1,3,7,15...第五个数字是几?第n个数字是几?

Answer 1

给出两个解:

(1) 0.282332 + 0.138675n + 0.571039n^2 + 0.00834818n^3 - 0.00637516n^4 + 0.00598056n^5;

(2) 2^n - 1;