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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.

A203656 T(n,k)=1/25 the number of (n+1)X(k+1) 0..4 arrays with every 2X2 subblock having equal diagonal elements or equal antidiagonal elements.

Table of values

n a(n)
1 9
2 81
3 81
4 729
5 1517
6 729
7 6561
8 28057
9 28057
10 6561
11 59049
12 519445
13 1116249
14 519445
15 59049
16 531441
17 9616161
18 44577561
19 44577561
20 9616161
21 531441
22 4782969
23 178019197
24 1780968921
25 3906948333
26 1780968921
27 178019197
28 4782969
29 43046721
30 3295578857

List of values

[9, 81, 81, 729, 1517, 729, 6561, 28057, 28057, 6561, 59049, 519445, 1116249, 519445, 59049, 531441, 9616161, 44577561, 44577561, 9616161, 531441, 4782969, 178019197, 1780968921, 3906948333, 1780968921, 178019197, 4782969, 43046721, 3295578857]

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

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