A115075 - cp's OEIS frontend

A115075 Number of 2 X 2 symmetric matrices over Z(n) having determinant 0.

n	a(n)
1	1
2	4
3	9
4	20
5	25
6	36
7	49
8	80
9	99
10	100
11	121
12	180
13	169
14	196
15	225
16	352
17	289
18	396
19	361
20	500
21	441
22	484
23	529
24	720
25	725
26	676
27	891
28	980
29	841
30	900
31	961
32	1408
33	1089
34	1156
35	1225
36	1980
37	1369
38	1444
39	1521
40	2000
41	1681
42	1764
43	1849
44	2420
45	2475
46	2116
47	2209
48	3168
49	2695
50	2900

[1, 4, 9, 20, 25, 36, 49, 80, 99, 100, 121, 180, 169, 196, 225, 352, 289, 396, 361, 500, 441, 484, 529, 720, 725, 676, 891, 980, 841, 900, 961, 1408, 1089, 1156, 1225, 1980, 1369, 1444, 1521, 2000, 1681, 1764, 1849, 2420, 2475, 2116, 2209, 3168, 2695, 2900]

cp's OEIS Frontend

A115075 Number of 2 X 2 symmetric matrices over Z(n) having determinant 0.

Table of values

List of values