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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.

A005164 Number of alternating sign 2n+1 X 2n+1 matrices invariant under all symmetries of the square.

Table of values

n a(n)
0 1
1 1
2 1
3 2
4 4
5 13
6 46
7 248
8 1516
9 13654
10 142873
11 2156888
12 38456356
13 974936056
14 29540545024
15 1259111024288
16 64726478396896
17 4641989615977216
18 404396533544588344
19 48825344233129714772
20 7202552030561982627472
21 1464587581921220811285325
22 365627222082497915618219716
23 125253905685915522767942493032
24 52893528399758443649956432899616

List of values

[1, 1, 1, 2, 4, 13, 46, 248, 1516, 13654, 142873, 2156888, 38456356, 974936056, 29540545024, 1259111024288, 64726478396896, 4641989615977216, 404396533544588344, 48825344233129714772, 7202552030561982627472, 1464587581921220811285325, 365627222082497915618219716, 125253905685915522767942493032, 52893528399758443649956432899616]

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

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