A374965 - cp's OEIS frontend

A374965 a(n) = 2*a(n-1) + 1 for a(n-1) not prime, otherwise a(n) = prime(n) - 1; with a(1)=1.

n	a(n)
1	1
2	3
3	4
4	9
5	19
6	12
7	25
8	51
9	103
10	28
11	57
12	115
13	231
14	463
15	46
16	93
17	187
18	375
19	751
20	70
21	141
22	283
23	82
24	165
25	331
26	100
27	201
28	403
29	807
30	1615
31	3231
32	6463
33	12927
34	25855
35	51711
36	103423
37	156
38	313
39	166
40	333
41	667
42	1335
43	2671
44	192
45	385
46	771
47	1543
48	222
49	445
50	891
51	1783
52	238
53	477

[1, 3, 4, 9, 19, 12, 25, 51, 103, 28, 57, 115, 231, 463, 46, 93, 187, 375, 751, 70, 141, 283, 82, 165, 331, 100, 201, 403, 807, 1615, 3231, 6463, 12927, 25855, 51711, 103423, 156, 313, 166, 333, 667, 1335, 2671, 192, 385, 771, 1543, 222, 445, 891, 1783, 238, 477]

cp's OEIS Frontend

A374965 a(n) = 2*a(n-1) + 1 for a(n-1) not prime, otherwise a(n) = prime(n) - 1; with a(1)=1.

Table of values

List of values