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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.

A000831 Expansion of e.g.f. (1 + tan(x))/(1 - tan(x)).

Table of values

n a(n)
0 1
1 2
2 4
3 16
4 80
5 512
6 3904
7 34816
8 354560
9 4063232
10 51733504
11 724566016
12 11070525440
13 183240753152
14 3266330312704
15 62382319599616
16 1270842139934720
17 27507470234550272
18 630424777638805504
19 15250953398036463616
20 388362339077351014400
21 10384044045105304174592

List of values

[1, 2, 4, 16, 80, 512, 3904, 34816, 354560, 4063232, 51733504, 724566016, 11070525440, 183240753152, 3266330312704, 62382319599616, 1270842139934720, 27507470234550272, 630424777638805504, 15250953398036463616, 388362339077351014400, 10384044045105304174592]

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

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