A261952 - cp's OEIS frontend

A261952 Start with a single equilateral triangle for n=0; for the odd n-th generation add a triangle at each expandable vertex of the triangles of the (n-1)-th generation (this is the "vertex to vertex" version); for the even n-th generation use the "side to side" version; a(n) is the number of triangles added in the n-th generation.

n	a(n)
0	1
1	3
2	9
3	18
4	18
5	24
6	27
7	33
8	36
9	42
10	45
11	51
12	54
13	60
14	63
15	69
16	72
17	78
18	81
19	87
20	90
21	96
22	99
23	105
24	108
25	114
26	117
27	123
28	126
29	132
30	135
31	141
32	144
33	150
34	153
35	159
36	162
37	168
38	171
39	177
40	180
41	186
42	189
43	195
44	198
45	204
46	207
47	213
48	216
49	222

[1, 3, 9, 18, 18, 24, 27, 33, 36, 42, 45, 51, 54, 60, 63, 69, 72, 78, 81, 87, 90, 96, 99, 105, 108, 114, 117, 123, 126, 132, 135, 141, 144, 150, 153, 159, 162, 168, 171, 177, 180, 186, 189, 195, 198, 204, 207, 213, 216, 222]

cp's OEIS Frontend

Table of values

List of values

n	a(n)
0	1
1	3
2	9
3	18
4	18
5	24
6	27
7	33
8	36
9	42
10	45
11	51
12	54
13	60
14	63
15	69
16	72
17	78
18	81
19	87
20	90
21	96
22	99
23	105
24	108
25	114
26	117
27	123
28	126
29	132
30	135
31	141
32	144
33	150
34	153
35	159
36	162
37	168
38	171
39	177
40	180
41	186
42	189
43	195
44	198
45	204
46	207
47	213
48	216
49	222

n	a(n)
0	1
1	3
2	9
3	18
4	18
5	24
6	27
7	33
8	36
9	42
10	45
11	51
12	54
13	60
14	63
15	69
16	72
17	78
18	81
19	87
20	90
21	96
22	99
23	105
24	108
25	114
26	117
27	123
28	126
29	132
30	135
31	141
32	144
33	150
34	153
35	159
36	162
37	168
38	171
39	177
40	180
41	186
42	189
43	195
44	198
45	204
46	207
47	213
48	216
49	222

n	a(n)
0	1
1	3
2	9
3	18
4	18
5	24
6	27
7	33
8	36
9	42
10	45
11	51
12	54
13	60
14	63
15	69
16	72
17	78
18	81
19	87
20	90
21	96
22	99
23	105
24	108
25	114
26	117
27	123
28	126
29	132
30	135
31	141
32	144
33	150
34	153
35	159
36	162
37	168
38	171
39	177
40	180
41	186
42	189
43	195
44	198
45	204
46	207
47	213
48	216
49	222