A261956 - cp's OEIS frontend

A261956 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 "side 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	6
3	9
4	12
5	18
6	15
7	21
8	21
9	36
10	39
11	54
12	36
13	54
14	39
15	57
16	45
17	72
18	63
19	90
20	60
21	90
22	63
23	93
24	69
25	108
26	87
27	126
28	84
29	126
30	87
31	129
32	93
33	144
34	111
35	162
36	108
37	162
38	111
39	165
40	117
41	180
42	135
43	198
44	132
45	198
46	135
47	201
48	141
49	216
50	159

[1, 3, 6, 9, 12, 18, 15, 21, 21, 36, 39, 54, 36, 54, 39, 57, 45, 72, 63, 90, 60, 90, 63, 93, 69, 108, 87, 126, 84, 126, 87, 129, 93, 144, 111, 162, 108, 162, 111, 165, 117, 180, 135, 198, 132, 198, 135, 201, 141, 216, 159]

cp's OEIS Frontend

Table of values

List of values

n	a(n)
0	1
1	3
2	6
3	9
4	12
5	18
6	15
7	21
8	21
9	36
10	39
11	54
12	36
13	54
14	39
15	57
16	45
17	72
18	63
19	90
20	60
21	90
22	63
23	93
24	69
25	108
26	87
27	126
28	84
29	126
30	87
31	129
32	93
33	144
34	111
35	162
36	108
37	162
38	111
39	165
40	117
41	180
42	135
43	198
44	132
45	198
46	135
47	201
48	141
49	216
50	159

n	a(n)
0	1
1	3
2	6
3	9
4	12
5	18
6	15
7	21
8	21
9	36
10	39
11	54
12	36
13	54
14	39
15	57
16	45
17	72
18	63
19	90
20	60
21	90
22	63
23	93
24	69
25	108
26	87
27	126
28	84
29	126
30	87
31	129
32	93
33	144
34	111
35	162
36	108
37	162
38	111
39	165
40	117
41	180
42	135
43	198
44	132
45	198
46	135
47	201
48	141
49	216
50	159

n	a(n)
0	1
1	3
2	6
3	9
4	12
5	18
6	15
7	21
8	21
9	36
10	39
11	54
12	36
13	54
14	39
15	57
16	45
17	72
18	63
19	90
20	60
21	90
22	63
23	93
24	69
25	108
26	87
27	126
28	84
29	126
30	87
31	129
32	93
33	144
34	111
35	162
36	108
37	162
38	111
39	165
40	117
41	180
42	135
43	198
44	132
45	198
46	135
47	201
48	141
49	216
50	159