A131868 - cp's OEIS frontend

A131868 a(n) = (2n^2)^(-1)Sum_{d|n} (-1)^(n+d)moebius(n/d)binomial(2*d,d).

n	a(n)
1	1
2	1
3	1
4	2
5	5
6	13
7	35
8	100
9	300
10	925
11	2915
12	9386
13	30771
14	102347
15	344705
16	1173960
17	4037381
18	14004912
19	48954659
20	172307930
21	610269695
22	2173656683
23	7782070631
24	27992709172
25	101128485150
26	366803656323
27	1335349400274
28	4877991428982

[1, 1, 1, 2, 5, 13, 35, 100, 300, 925, 2915, 9386, 30771, 102347, 344705, 1173960, 4037381, 14004912, 48954659, 172307930, 610269695, 2173656683, 7782070631, 27992709172, 101128485150, 366803656323, 1335349400274, 4877991428982]

cp's OEIS Frontend

A131868 a(n) = (2n^2)^(-1)Sum_{d|n} (-1)^(n+d)moebius(n/d)binomial(2*d,d).

Table of values

List of values

cp's OEIS Frontend

A131868 a(n) = (2*n^2)^(-1)*Sum_{d|n} (-1)^(n+d)*moebius(n/d)*binomial(2*d,d).

Table of values

List of values

A131868 a(n) = (2n^2)^(-1)Sum_{d|n} (-1)^(n+d)moebius(n/d)binomial(2*d,d).