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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.

A058157 Triangle read by rows: T(n,k) is the number of labeled monoids of order n with k idempotents.

Table of values

n a(n)
1 1
2 2
3 2
4 3
5 18
6 12
7 16
8 180
9 288
10 140
11 30
12 2640
13 6540
14 8380
15 3020
16 480
17 119610
18 238200
19 421020
20 372360
21 100362
22 840
23 25196052
24 13786290
25 26803000
26 36174600
27 22822674
28 4768624
29 22080
30 48687313640
31 2254725312
32 2358499080
33 3849768160
34 3859581096
35 1826525120
36 305498328

List of values

[1, 2, 2, 3, 18, 12, 16, 180, 288, 140, 30, 2640, 6540, 8380, 3020, 480, 119610, 238200, 421020, 372360, 100362, 840, 25196052, 13786290, 26803000, 36174600, 22822674, 4768624, 22080, 48687313640, 2254725312, 2358499080, 3849768160, 3859581096, 1826525120, 305498328]

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

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