A123247 - cp's OEIS frontend

A123247 Let S(1)={1} and, for n>1 let S(n) be the smallest set containing x, x+1, 2x and 3x for each element x in S(n-1). a(n) is the number of elements in S(n).

n	a(n)
1	1
2	3
3	6
4	13
5	27
6	54
7	107
8	213
9	423
10	845
11	1685
12	3371
13	6735
14	13468
15	26937
16	53900
17	107873
18	216035
19	432787
20	867313
21	1738728
22	3486464
23	6993111
24	14029776
25	28153533
26	56507114
27	113435141
28	227755613
29	457358671
30	918562597

[1, 3, 6, 13, 27, 54, 107, 213, 423, 845, 1685, 3371, 6735, 13468, 26937, 53900, 107873, 216035, 432787, 867313, 1738728, 3486464, 6993111, 14029776, 28153533, 56507114, 113435141, 227755613, 457358671, 918562597]

cp's OEIS Frontend

A123247 Let S(1)={1} and, for n>1 let S(n) be the smallest set containing x, x+1, 2x and 3x for each element x in S(n-1). a(n) is the number of elements in S(n).

Table of values

List of values