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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.

A268592 a(n) = (6/n^3) * Sum_{d|n} moebius(n/d)*binomial(2*d,d).

Table of values

n a(n)
1 12
2 3
3 4
4 6
5 12
6 25
7 60
8 150
9 400
10 1107
11 3180
12 9386
13 28404
14 87711
15 275764
16 880470
17 2849916
18 9336508
19 30918732
20 103384758
21 348725540
22 1185630123
23 4060210764
24 13996354586
25 48541672872
26 169293988125
27 593488622344
28 2090567755278
29 7396924802052
30 26281018091013
31 93738717046476
32 335563502259798

List of values

[12, 3, 4, 6, 12, 25, 60, 150, 400, 1107, 3180, 9386, 28404, 87711, 275764, 880470, 2849916, 9336508, 30918732, 103384758, 348725540, 1185630123, 4060210764, 13996354586, 48541672872, 169293988125, 593488622344, 2090567755278, 7396924802052, 26281018091013, 93738717046476, 335563502259798]

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

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