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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.

A058159 Triangle read by rows: T(n,k) is the number of labeled commutative monoids of order n with k idempotents.

Table of values

n a(n)
1 1
2 2
3 2
4 3
5 18
6 6
7 16
8 180
9 144
10 36
11 30
12 2040
13 3240
14 1740
15 380
16 360
17 43170
18 81000
19 70740
20 31680
21 6390
22 840
23 1400112
24 2589510
25 2976960
26 2055480
27 832230
28 157962
29 15360
30 110488616
31 117733728
32 144285960
33 130781280
34 79626120
35 30004128
36 5396888
37 68040
38 30647444544
39 9223088112
40 8744866704
41 8997002280
42 7154708400
43 4005012816
44 1421659512
45 243179064

List of values

[1, 2, 2, 3, 18, 6, 16, 180, 144, 36, 30, 2040, 3240, 1740, 380, 360, 43170, 81000, 70740, 31680, 6390, 840, 1400112, 2589510, 2976960, 2055480, 832230, 157962, 15360, 110488616, 117733728, 144285960, 130781280, 79626120, 30004128, 5396888, 68040, 30647444544, 9223088112, 8744866704, 8997002280, 7154708400, 4005012816, 1421659512, 243179064]

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

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