17/11/15 23:31:55.04 bRQyF7b9.net
>>41
Σ[k=1，n］1/k ≒ 1 + ∫[3/2, n+1/2］(1/x)dx = 1 +［ log(x）］(x=3/2→n+1/2) = 1 + log((2n+1)/3),
Σ[k=1，20］1/k ≒ 1 + log((2*20+1)/3）= 3.61495978
Σ[k=1，80］1/k ≒ 1 + log((2*80+1)/3）= 4.98279208
→ 0.72549
Σ[k=1，n］1/k ≒ 3/2 + ∫[5/2, n+1/2］(1/x)dx = 3/2 +［ log(x）］(x=5/2→n+1/2) = 3/2 + log((2n+1)/5),
Σ[k=1，20］1/k ≒ 3/2 + log((2*20+1)/5）= 3.60413415
Σ[k=1，80］1/k ≒ 3/2 + log((2*80+1)/5）= 4.97196645
→ 0.72489
Σ[k=1，n］1/k ≒ 11/6 + ∫[7/2, n+1/2］(1/x)dx = 11/6 +［ log(x）］(x=7/2→n+1/2) = 11/6 + log((2n+1)/7),
Σ[k=1，20］1/k ≒ 11/6 + log((2*20+1)/7）= 3.60099525
Σ[k=1，80］1/k ≒ 11/6 + log((2*80+1)/7）= 4.96882755
→ 0.72472