A181945 - cp's OEIS frontend

A181945 Number of trapezoids, distinct up to congruence, on an n X n grid (or geoboard).

n	a(n)
1	0
2	1
3	9
4	43
5	141
6	343
7	766
8	1415
9	2517
10	4129
11	6545
12	9505
13	14230
14	19444
15	26733
16	36208
17	48029
18	60675
19	78729
20	96866
21	122433
22	151288
23	184072
24	217998
25	266775
26	315096
27	371138
28	435153
29	512549
30	585240
31	688470
32	779196
33	895058
34	1019697
35	1153081
36	1305629
37	1494185
38	1656287

[0, 1, 9, 43, 141, 343, 766, 1415, 2517, 4129, 6545, 9505, 14230, 19444, 26733, 36208, 48029, 60675, 78729, 96866, 122433, 151288, 184072, 217998, 266775, 315096, 371138, 435153, 512549, 585240, 688470, 779196, 895058, 1019697, 1153081, 1305629, 1494185, 1656287]

cp's OEIS Frontend

A181945 Number of trapezoids, distinct up to congruence, on an n X n grid (or geoboard).

Table of values

List of values