A321257 - cp's OEIS frontend

A321257 Start with an equilateral triangle, and repeatedly append along the triangles of the previous step equilateral triangles with half their side length that do not overlap with any prior triangle; a(n) gives the number of triangles appended at n-th step.

n	a(n)
1	1
2	6
3	21
4	60
5	147
6	330
7	705
8	1464
9	2991
10	6054
11	12189
12	24468
13	49035
14	98178
15	196473
16	393072
17	786279
18	1572702
19	3145557
20	6291276
21	12582723
22	25165626
23	50331441
24	100663080
25	201326367
26	402652950
27	805306125
28	1610612484
29	3221225211
30	6442450674
31	12884901609
32	25769803488

[1, 6, 21, 60, 147, 330, 705, 1464, 2991, 6054, 12189, 24468, 49035, 98178, 196473, 393072, 786279, 1572702, 3145557, 6291276, 12582723, 25165626, 50331441, 100663080, 201326367, 402652950, 805306125, 1610612484, 3221225211, 6442450674, 12884901609, 25769803488]

cp's OEIS Frontend

A321257 Start with an equilateral triangle, and repeatedly append along the triangles of the previous step equilateral triangles with half their side length that do not overlap with any prior triangle; a(n) gives the number of triangles appended at n-th step.

Table of values

List of values