2^6+2^(n-1)+2^(n-2)+...+2^3+2^2+2+1怎么写

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 2^n/n*(n+1) lim[n/(n*n+1*1)+n/(n*n+2*2)+...+n/(n*n+n*n)],当x趋向无穷大时,怎么求极限, 化简(n+1)(n+2)(n+3) 数列a(n)=n (n+1)(n+2)(n+3), 求S(n)怎么用高中数列原理解答? 计算：n(n+1)(n+2)(n+3)+1 lim[(n+3)/(n+1))]^(n-2) 【n无穷大】 (1/(n^2 n 1 ) 2/(n^2 n 2) 3/(n^2 n 3) ……n/(n^2 n n)) 当N越于无穷大 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).. 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? 1 + (n + 1) + n*(n + 1) + n*n + (n + 1) + 1 = 2n^2 + 3n + 3