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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.

A140304 Number of n X n binary matrices with no more than one 1 in any 3 X 3 sub-block.

Table of values

n a(n)
0 1
1 2
2 5
3 10
4 60
5 437
6 2875
7 36409
8 704468
9 14783959
10 461938624
11 22488554884
12 1378748967395
13 115759328877461
14 14408020654986447
15 2435526103569141336
16 559083220302137929773
17 182904062593977747117174
18 83283166161035345074485948
19 52012981990902321891650583747
20 45449967513840995133445585972949

List of values

[1, 2, 5, 10, 60, 437, 2875, 36409, 704468, 14783959, 461938624, 22488554884, 1378748967395, 115759328877461, 14408020654986447, 2435526103569141336, 559083220302137929773, 182904062593977747117174, 83283166161035345074485948, 52012981990902321891650583747, 45449967513840995133445585972949]

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

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