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Harmonic series (mathematics)

The first thirty harmonic numbers
n Partial sum of the harmonic series, Hn
expressed as a fraction decimal relative size
1 1 ~1 1
 
2 3 /2 ~1.5 1.5
 
3 11 /6 ~1.83333 1.83333
 
4 25 /12 ~2.08333 2.08333
 
5 137 /60 ~2.28333 2.28333
 
6 49 /20 ~2.45 2.45
 
7 363 /140 ~2.59286 2.59286
 
8 761 /280 ~2.71786 2.71786
 
9 7129 /2520 ~2.82897 2.82897
 
10 7381 /2520 ~2.92897 2.92897
 
11 83711 /27720 ~3.01988 3.01988
 
12 86021 /27720 ~3.10321 3.10321
 
13 1145993 /360360 ~3.18013 3.18013
 
14 1171733 /360360 ~3.25156 3.25156
 
15 1195757 /360360 ~3.31823 3.31823
 
16 2436559 /720720 ~3.38073 3.38073
 
17 42142223 /12252240 ~3.43955 3.43955
 
18 14274301 /4084080 ~3.49511 3.49511
 
19 275295799 /77597520 ~3.54774 3.54774
 
20 55835135 /15519504 ~3.59774 3.59774
 
21 18858053 /5173168 ~3.64536 3.64536
 
22 19093197 /5173168 ~3.69081 3.69081
 
23 444316699 /118982864 ~3.73429 3.73429
 
24 1347822955 /356948592 ~3.77596 3.77596
 
25 34052522467 /8923714800 ~3.81596 3.81596
 
26 34395742267 /8923714800 ~3.85442 3.85442
 
27 312536252003 /80313433200 ~3.89146 3.89146
 
28 315404588903 /80313433200 ~3.92717 3.92717
 
29 9227046511387 /2329089562800 ~3.96165 3.96165
 
30 9304682830147 /2329089562800 ~3.99499 3.99499
 

In mathematics, the harmonic series is the divergent infinite series:

Its name derives from the concept of overtones, or harmonics in music: the wavelengths of the overtones of a vibrating string are 1/2, 1/3, 1/4, etc., of the string's fundamental wavelength. Every term of the series after the first is the harmonic mean of the neighboring terms; the phrase harmonic mean likewise derives from music.

The fact that the harmonic series diverges was first proven in the 14th century by Nicole Oresme, but this achievement fell into obscurity. Proofs were given in the 17th century by Pietro Mengoli,Johann Bernoulli, and Jacob Bernoulli.

Historically, harmonic sequences have had a certain popularity with architects. This was so particularly in the Baroque period, when architects used them to establish the proportions of floor plans, of elevations, and to establish harmonic relationships between both interior and exterior architectural details of churches and palaces.


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