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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.

A326878 Number of topologies whose points are a subset of {1..n}.

Table of values

n a(n)
0 1
1 2
2 7
3 45
4 500
5 9053
6 257151
7 11161244
8 725343385
9 69407094565
10 9639771895398
11 1919182252611715
12 541764452276876719
13 214777343584048313318
14 118575323291814379721651
15 90492591258634595795504697
16 94844885130660856889237907260
17 135738086271526574073701454370969
18 263921383510041055422284977248713291

List of values

[1, 2, 7, 45, 500, 9053, 257151, 11161244, 725343385, 69407094565, 9639771895398, 1919182252611715, 541764452276876719, 214777343584048313318, 118575323291814379721651, 90492591258634595795504697, 94844885130660856889237907260, 135738086271526574073701454370969, 263921383510041055422284977248713291]

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

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