1-1/2-1/3-1/4-……-1/n的和求公式
1-1/2-1/3-1/4-……-1/n
= 2-1-1/2-1/3-1/4-……-1/n
= 2-(1/1+1/2+1/3+1/4+......+1/n)
括号中为正整数倒数，也称作调和数列。迄今为止，数学家们还没有找到调和数列的求和公式。
因此，本题所列算式，没有直接的求和公式。只能手工计算，或者编程，或者利用在线工具求解。
编程计算了n=[2,100]的近似值，如下：
S2 = 0.50000000000000；S3 = 0.16666666666667；S4 = -0.08333333333333；
S5 = -0.28333333333333；S6 = -0.45000000000000；S7 = -0.59285714285714；
S8 = -0.71785714285714；S9 = -0.82896825396825；S10 = -0.92896825396825；
S11 = -1.01987734487734；S12 = -1.10321067821068；S13 = -1.18013375513375；
S14 = -1.25156232656233；S15 = -1.31822899322899；S16 = -1.38072899322899；
S17 = -1.43955252264076；S18 = -1.49510807819631；S19 = -1.54773965714368；
S20 = -1.59773965714368；S21 = -1.64535870476273；S22 = -1.69081325021727；
S23 = -1.73429151108684；S24 = -1.77595817775351；S25 = -1.81595817775351；
S26 = -1.85441971621505；S27 = -1.89145675325208；S28 = -1.92717103896637；
S29 = -1.96165379758706；S30 = -1.99498713092039；S31 = -2.02724519543652；
S32 = -2.05849519543652；S33 = -2.08879822573955；S34 = -2.11820999044543；
S35 = -2.14678141901686；S36 = -2.17455919679464；S37 = -2.20158622382167；
S38 = -2.22790201329535；S39 = -2.25354303893638；S40 = -2.27854303893638；
S41 = -2.30293328283881；S42 = -2.32674280664834；S43 = -2.34999862060183；
S44 = -2.37272589332910；S45 = -2.39494811555132；S46 = -2.41668724598610；
S47 = -2.43796384173079；S48 = -2.45879717506412；S49 = -2.47920533832943；
S50 = -2.49920533832943；S51 = -2.51881318146668；S52 = -2.53804395069745；
S53 = -2.55691187522575；S54 = -2.57543039374427；S55 = -2.59361221192609；
S56 = -2.61146935478323；S57 = -2.62901321443235；S58 = -2.64625459374270；
S59 = -2.66320374628507；S60 = -2.67987041295174；S61 = -2.69626385557469；
S62 = -2.71239288783275；S63 = -2.72826590370577；S64 = -2.74389090370577；
S65 = -2.75927551909038；S66 = -2.77442703424190；S67 = -2.78935240737623；
S68 = -2.80405828972917；S69 = -2.81855104335236；S70 = -2.83283675763807；
S71 = -2.84692126468032；S72 = -2.86081015356921；S73 = -2.87450878370620；
S74 = -2.88802229721971；S75 = -2.90135563055305；S76 = -2.91451352528989；
S77 = -2.92750053827690；S78 = -2.94032105109741；S79 = -2.95297927894552；
S80 = -2.96547927894552；S81 = -2.97782495795786；S82 = -2.99002007990908；
S83 = -3.00206827268017；S84 = -3.01397303458493；S85 = -3.02573774046728；
S86 = -3.03736564744402；S87 = -3.04885990031759；S88 = -3.06022353668122；
S89 = -3.07145949173740；S90 = -3.08257060284852；S91 = -3.09355961383753；
S92 = -3.10442917905492；S93 = -3.11518186722696；S94 = -3.12582016509930；
S95 = -3.13634648088877；S96 = -3.14676314755544；S97 = -3.15707242590596；
S98 = -3.16727650753861；S99 = -3.17737751763962；S100 = -3.18737751763962；
附：fortran代码，供参考
