A257970 - cp's OEIS frontend

A257970 a(1) = 1, a(2) = 2, a(3) = 5; thereafter a(n) = 2 * Sum_{k=1..n-1} a(k).

n	a(n)
1	1
2	2
3	5
4	16
5	48
6	144
7	432
8	1296
9	3888
10	11664
11	34992
12	104976
13	314928
14	944784
15	2834352
16	8503056
17	25509168
18	76527504
19	229582512
20	688747536
21	2066242608
22	6198727824
23	18596183472
24	55788550416
25	167365651248
26	502096953744
27	1506290861232
28	4518872583696
29	13556617751088

[1, 2, 5, 16, 48, 144, 432, 1296, 3888, 11664, 34992, 104976, 314928, 944784, 2834352, 8503056, 25509168, 76527504, 229582512, 688747536, 2066242608, 6198727824, 18596183472, 55788550416, 167365651248, 502096953744, 1506290861232, 4518872583696, 13556617751088]

cp's OEIS Frontend

A257970 a(1) = 1, a(2) = 2, a(3) = 5; thereafter a(n) = 2 * Sum_{k=1..n-1} a(k).

Table of values

List of values