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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.

A240456 Number of nX2 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4.

Table of values

n a(n)
1 4
2 21
3 102
4 476
5 2200
6 10123
7 46471
8 213000
9 975380
10 4464474
11 20429739
12 93474260
13 427645941
14 1956395954
15 8949898045
16 40942368765
17 187294120155
18 856787747966
19 3919414321141
20 17929510264717
21 82019155503670
22 375199231601451

List of values

[4, 21, 102, 476, 2200, 10123, 46471, 213000, 975380, 4464474, 20429739, 93474260, 427645941, 1956395954, 8949898045, 40942368765, 187294120155, 856787747966, 3919414321141, 17929510264717, 82019155503670, 375199231601451]

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

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