A123765 - cp's OEIS frontend

A123765 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 2 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

n	a(n)
1	1
2	1
3	3
4	4
5	12
6	18
7	52
8	83
9	235
10	389
11	1087
12	1851
13	5113
14	8891
15	24357
16	43045
17	117127
18	209731
19	567487
20	1027245
21	2766404
22	5053521
23	13554315
24	24954627
25	66696366
26	123628610
27	329400200
28	614216837
29	1632039074
30	3059240151
31	8108703876

[1, 1, 3, 4, 12, 18, 52, 83, 235, 389, 1087, 1851, 5113, 8891, 24357, 43045, 117127, 209731, 567487, 1027245, 2766404, 5053521, 13554315, 24954627, 66696366, 123628610, 329400200, 614216837, 1632039074, 3059240151, 8108703876]

cp's OEIS Frontend

A123765 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 2 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

Table of values

List of values