设a1,a2,a3···an是1,2,3···n的某种排列,且n是奇数,那么(a1-1)(a2-2)(a3-3)···(
设a1,a2,a3···an是1,2,3···n的某种排列,且n是奇数,那么(a1-1)(a2-2)(a3-3)···(
设a1,a2,a3……an是1,2,3……n的某种排列,且n是奇数,那么
设数列【an】满足a1=1,3(a1+a2+a3+······+an)=(n+2)an,求通项an
设a1,a2…an是1,2…,n的一个排列,求证1/2+2/3+..+(n-1)/n≤a1/a2+a2/a3+...+a
设a1,a2...an是1,2...n的一个排列求证1/2+2/3+...+n-1/n小于等于a1/a2+a2/a3+.
数列{an}通项公式是(-1)^n·(2n-1),则a1+a2+a3+...+a100等于
设数列{an}满足a1+3a2+3^2a3+······+3^(n-1)an=n/3,a∈N*.(1)求数列{an}的通
设数列{an}的前n项和为Sn,a1=1,且3a(n+1)=Sn,(1)求a2,a3,a4及an (2)求a2+a4+·
数列{an}中,a1+a2+a3···+an=2n+1(n∈N※),求an
已知{an}为等差数列,且a1=2,a1+a2+a3=12.(1)求数列{an}的通项公式(2)令bn=an·3^n,求
已知数列{An}为等差数列,且A1=2,A1+A2+A3=12,令Bn=An·3的n次方(n属于整数)求{Bn}的前n项
设数列an满足a1=a2=1,a3=2,且对正整数n都有an·an+1·an+2·an+3=an+an+1+an+2+a