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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.

A083691 Length of list generated by n replacements of k by {-1-|k|, ..., 1+|k|} with increment 2, starting with {0}.

Table of values

n a(n)
0 1
1 2
2 6
3 20
4 76
5 296
6 1240
7 5200
8 22960
9 100512
10 458592
11 2064704
12 9633472
13 44237440
14 209780096
15 977536256
16 4693031680
17 22117091840
18 107211650560
19 509817656320
20 2490609167360
21 11930278307840
22 58656838113280
23 282679983493120

List of values

[1, 2, 6, 20, 76, 296, 1240, 5200, 22960, 100512, 458592, 2064704, 9633472, 44237440, 209780096, 977536256, 4693031680, 22117091840, 107211650560, 509817656320, 2490609167360, 11930278307840, 58656838113280, 282679983493120]

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

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