1/2+1/6+1/12+`````+1/n(n+1)=2003/2004,n为多少?
n(n+1)(n+2)等于多少?
1\n(n+3)+1\(n+3)(n+6)+1\(n+6)(n+9)=1\2 n+18 n为正整数,求n的值
Sn=n(n+2)(n+4)的分项等于1/6[n(n+2)(n+4)(n+5)-(n-1)n(n+2)(n+4)]吗?
2^n/n*(n+1)
[(1+n)n]/2*6等于多少?
(n+1)^n-(n-1)^n=?
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
根号下n(n+2)+1= n为自然数
当n为正偶数,求证n/(n-1)+n(n-2)/(n-1)(n-3)+...+n(n-2).2/(n-1)(n-3)..
(-1)2n+1次方为多少(n为自然数)
阶乘(2n-1)!=(2n)!/(2^n*n!