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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.

A306445 Number of collections of subsets of {1, 2, ..., n} that are closed under union and intersection.

Table of values

n a(n)
0 2
1 4
2 13
3 74
4 732
5 12085
6 319988
7 13170652
8 822378267
9 76359798228
10 10367879036456
11 2029160621690295
12 565446501943834078
13 221972785233309046708
14 121632215040070175606989
15 92294021880898055590522262
16 96307116899378725213365550192
17 137362837456925278519331211455157
18 266379254536998812281897840071155592

List of values

[2, 4, 13, 74, 732, 12085, 319988, 13170652, 822378267, 76359798228, 10367879036456, 2029160621690295, 565446501943834078, 221972785233309046708, 121632215040070175606989, 92294021880898055590522262, 96307116899378725213365550192, 137362837456925278519331211455157, 266379254536998812281897840071155592]

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

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