已知1^2+2^2+…+n^2=1/6n(n+1)(2n+1),计算:(1)11^2+12^2+…+19^2=( )(2
2^n/n*(n+1)
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
计算:n(n+1)(n+2)(n+3)+1
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?
计算:C(1,n)+2C(2,n)+3C(3,n) + … + nC(n,n)
组合:C(n,0)+C(n,1)+……+C(n,n)=n^2
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
阶乘(2n-1)!=(2n)!/(2^n*n!
求极限 lim n[1/(n^2+1)+1/(n^2+2^2)+……+1/(n^n+n^n)] (n趋向于无穷大,n^n
编写程序,输入正整数N,计算它的阶乘N!(N!=N*(N-1)*…*3*2*1)
编写程序,输入正整数n,计算它的阶乘n!(n!=n×(n-1)×…×3×2×1).
(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