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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.

A230658 Number of nX3 0..2 black square subarrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value 2-x(i,j).

Table of values

n a(n)
1 0
2 3
3 15
4 21
5 135
6 177
7 1155
8 1509
9 9855
10 12873
11 84075
12 109821
13 717255
14 936897
15 6118995
16 7992789
17 52201935
18 68187513
19 445341435
20 581716461
21 3799265175
22 4962698097
23 32412020835
24 42337417029
25 276511126815
26 361185960873

List of values

[0, 3, 15, 21, 135, 177, 1155, 1509, 9855, 12873, 84075, 109821, 717255, 936897, 6118995, 7992789, 52201935, 68187513, 445341435, 581716461, 3799265175, 4962698097, 32412020835, 42337417029, 276511126815, 361185960873]

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

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