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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.

A006897 a(n) is the number of hierarchical linear models on n unlabeled factors allowing 2-way interactions (but no higher order interactions); or the number of unlabeled simple graphs with <= n nodes.

Table of values

n a(n)
0 1
1 2
2 4
3 8
4 19
5 53
6 209
7 1253
8 13599
9 288267
10 12293435
11 1031291299
12 166122463891
13 50668153831843
14 29104823811067331
15 31455590793615376099
16 64032471295321173271027
17 245999896624828253856990803
18 1787823725042236528801735181651
19 24639597076850046760911809226614419

List of values

[1, 2, 4, 8, 19, 53, 209, 1253, 13599, 288267, 12293435, 1031291299, 166122463891, 50668153831843, 29104823811067331, 31455590793615376099, 64032471295321173271027, 245999896624828253856990803, 1787823725042236528801735181651, 24639597076850046760911809226614419]

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

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