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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A382257 a(n) is the numerator of tanh(Sum_{k=1..n-1} artanh(k/n)), where artanh is the inverse hyperbolic tangent function.

Table of values

n a(n)
1 0
2 1
3 9
4 17
5 125
6 461
7 1715
8 3217
9 24309
10 92377
11 352715
12 1352077
13 5200299
14 20058299
15 77558759
16 150270097
17 1166803109
18 4537567649
19 17672631899
20 68923264409
21 269128937219
22 1052049481859
23 4116715363799
24 16123801841549
25 63205303218875
26 247959266474051
27 973469712824055
28 3824345300380219
29 15033633249770519

List of values

[0, 1, 9, 17, 125, 461, 1715, 3217, 24309, 92377, 352715, 1352077, 5200299, 20058299, 77558759, 150270097, 1166803109, 4537567649, 17672631899, 68923264409, 269128937219, 1052049481859, 4116715363799, 16123801841549, 63205303218875, 247959266474051, 973469712824055, 3824345300380219, 15033633249770519]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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