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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.

A063887 Number of n-step walks on a square lattice starting from the origin but not returning to it at any stage.

Table of values

n a(n)
0 1
1 4
2 12
3 48
4 172
5 688
6 2576
7 10304
8 39340
9 157360
10 607376
11 2429504
12 9442448
13 37769792
14 147495104
15 589980416
16 2311926188
17 9247704752
18 36333781776
19 145335127104
20 572189853200
21 2288759412800
22 9025822792896
23 36103291171584
24 142567754881168
25 570271019524672
26 2254477964009664
27 9017911856038656

List of values

[1, 4, 12, 48, 172, 688, 2576, 10304, 39340, 157360, 607376, 2429504, 9442448, 37769792, 147495104, 589980416, 2311926188, 9247704752, 36333781776, 145335127104, 572189853200, 2288759412800, 9025822792896, 36103291171584, 142567754881168, 570271019524672, 2254477964009664, 9017911856038656]

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

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