A268619 - cp's OEIS frontend

A268619 a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)binomial(2d,d).

n	a(n)
1	2
2	1
3	2
4	4
5	10
6	25
7	70
8	200
9	600
10	1845
11	5830
12	18772
13	61542
14	204659
15	689410
16	2347920
17	8074762
18	28009524
19	97909318
20	344615860
21	1220539390
22	4347310451
23	15564141262
24	55985418344
25	202256970300
26	733607281875
27	2670698800548
28	9755982857964
29	35751803209918
30	131405090455065
31	484316704740126
32	1789672012052256

[2, 1, 2, 4, 10, 25, 70, 200, 600, 1845, 5830, 18772, 61542, 204659, 689410, 2347920, 8074762, 28009524, 97909318, 344615860, 1220539390, 4347310451, 15564141262, 55985418344, 202256970300, 733607281875, 2670698800548, 9755982857964, 35751803209918, 131405090455065, 484316704740126, 1789672012052256]

cp's OEIS Frontend

A268619 a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)binomial(2d,d).

Table of values

List of values

cp's OEIS Frontend

A268619 a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)*binomial(2*d,d).

Table of values

List of values

A268619 a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)binomial(2d,d).