0145132人目の素数さん
2018/08/12(日) 08:57:27.11ID:QnRFj99l[a+b] = [a] + [b] + [{a}+{b}] ≧ [a] + [b],
j≧2 のとき
S_j = (j-1)・[jx] - 2Σ(k=1,j-1) [kx]
= Σ(k=1,j-1) ( [jx] - [kx] - [(j-k)x] )
≧ 0,
f(x) = [nx] - Σ(k=1,n) [kx]/k
= Σ(j=2,n-1) (1/j - 1/(j+1))・S_j + (1/n)・S_n
≧ 0,