A261953 - cp's OEIS frontend

A261953 Start with a single equilateral triangle for n=0; for the odd n-th generation add a triangle at each expandable side of the triangles of the (n-1)-th generation (this is the "side to side" version); for the even n-th generation use the "vertex to vertex" version; a(n) is the number of triangles added in the n-th generation.

n	a(n)
0	1
1	3
2	9
3	12
4	18
5	21
6	27
7	30
8	36
9	39
10	45
11	48
12	54
13	57
14	63
15	66
16	72
17	75
18	81
19	84
20	90
21	93
22	99
23	102
24	108
25	111
26	117
27	120
28	126
29	129
30	135
31	138
32	144
33	147
34	153
35	156
36	162
37	165
38	171
39	174
40	180
41	183
42	189
43	192
44	198
45	201
46	207
47	210
48	216
49	219
50	225
51	228
52	234
53	237
54	243
55	246
56	252

[1, 3, 9, 12, 18, 21, 27, 30, 36, 39, 45, 48, 54, 57, 63, 66, 72, 75, 81, 84, 90, 93, 99, 102, 108, 111, 117, 120, 126, 129, 135, 138, 144, 147, 153, 156, 162, 165, 171, 174, 180, 183, 189, 192, 198, 201, 207, 210, 216, 219, 225, 228, 234, 237, 243, 246, 252]

cp's OEIS Frontend

Table of values

List of values

n	a(n)
0	1
1	3
2	9
3	12
4	18
5	21
6	27
7	30
8	36
9	39
10	45
11	48
12	54
13	57
14	63
15	66
16	72
17	75
18	81
19	84
20	90
21	93
22	99
23	102
24	108
25	111
26	117
27	120
28	126
29	129
30	135
31	138
32	144
33	147
34	153
35	156
36	162
37	165
38	171
39	174
40	180
41	183
42	189
43	192
44	198
45	201
46	207
47	210
48	216
49	219
50	225
51	228
52	234
53	237
54	243
55	246
56	252

n	a(n)
0	1
1	3
2	9
3	12
4	18
5	21
6	27
7	30
8	36
9	39
10	45
11	48
12	54
13	57
14	63
15	66
16	72
17	75
18	81
19	84
20	90
21	93
22	99
23	102
24	108
25	111
26	117
27	120
28	126
29	129
30	135
31	138
32	144
33	147
34	153
35	156
36	162
37	165
38	171
39	174
40	180
41	183
42	189
43	192
44	198
45	201
46	207
47	210
48	216
49	219
50	225
51	228
52	234
53	237
54	243
55	246
56	252

n	a(n)
0	1
1	3
2	9
3	12
4	18
5	21
6	27
7	30
8	36
9	39
10	45
11	48
12	54
13	57
14	63
15	66
16	72
17	75
18	81
19	84
20	90
21	93
22	99
23	102
24	108
25	111
26	117
27	120
28	126
29	129
30	135
31	138
32	144
33	147
34	153
35	156
36	162
37	165
38	171
39	174
40	180
41	183
42	189
43	192
44	198
45	201
46	207
47	210
48	216
49	219
50	225
51	228
52	234
53	237
54	243
55	246
56	252