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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.

A240371 Number of nX2 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

Table of values

n a(n)
1 3
2 11
3 21
4 67
5 155
6 353
7 998
8 2256
9 5639
10 14624
11 34169
12 87040
13 216484
14 522354
15 1320708
16 3242252
17 7968236
18 19928605
19 48905783
20 121065218
21 300575628
22 739878493
23 1834210821
24 4538220894
25 11200994822
26 27751051195
27 68588966317
28 169541251841

List of values

[3, 11, 21, 67, 155, 353, 998, 2256, 5639, 14624, 34169, 87040, 216484, 522354, 1320708, 3242252, 7968236, 19928605, 48905783, 121065218, 300575628, 739878493, 1834210821, 4538220894, 11200994822, 27751051195, 68588966317, 169541251841]

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

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