A115004 - cp's OEIS frontend

A115004 a(n) = Sum_{i=1..n, j=1..n, gcd(i,j)=1} (n+1-i)*(n+1-j).

n	a(n)
1	1
2	8
3	31
4	80
5	179
6	332
7	585
8	948
9	1463
10	2136
11	3065
12	4216
13	5729
14	7568
15	9797
16	12456
17	15737
18	19520
19	24087
20	29308
21	35315
22	42120
23	50073
24	58920
25	69025
26	80264
27	92871
28	106756
29	122475
30	139528
31	158681
32	179608
33	202529
34	227400
35	254597
36	283784
37	315957
38	350576
39	387977

[1, 8, 31, 80, 179, 332, 585, 948, 1463, 2136, 3065, 4216, 5729, 7568, 9797, 12456, 15737, 19520, 24087, 29308, 35315, 42120, 50073, 58920, 69025, 80264, 92871, 106756, 122475, 139528, 158681, 179608, 202529, 227400, 254597, 283784, 315957, 350576, 387977]

cp's OEIS Frontend

A115004 a(n) = Sum_{i=1..n, j=1..n, gcd(i,j)=1} (n+1-i)*(n+1-j).

Table of values

List of values