来自孙崇峰的问题
数列1，2+12，3+12+14，…，n+12+14+…+12n−1的前n项和为（）A.n+1-(12)n−1B.12n2+32n+12n−1-3C.12n2+32n+12n−1-2D.n+12n−1-1
数列1，2+12，3+12+14，…，n+12+14+…+12n−1的前n项和为（）
A.n+1-(12)n−1
B.12n2+32n+12n−1-3
C.12n2+32n+12n−1-2
D.n+12n−1-1
