A078440 - cp's OEIS frontend

A078440 Numbers n with property that n is not a power of 2 and the finite sequence n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem contains exactly one prime. (The earliest "1" is meant.)

n	a(n)
1	21
2	42
3	84
4	85
5	168
6	170
7	336
8	340
9	341
10	453
11	672
12	680
13	682
14	906
15	909
16	1344
17	1360
18	1364
19	1365
20	1812
21	1813
22	1818
23	2688
24	2720
25	2728
26	2730
27	3624
28	3626
29	3636
30	5376
31	5440
32	5456
33	5460
34	5461
35	7248
36	7252
37	7272
38	7281
39	9669

[21, 42, 84, 85, 168, 170, 336, 340, 341, 453, 672, 680, 682, 906, 909, 1344, 1360, 1364, 1365, 1812, 1813, 1818, 2688, 2720, 2728, 2730, 3624, 3626, 3636, 5376, 5440, 5456, 5460, 5461, 7248, 7252, 7272, 7281, 9669]

cp's OEIS Frontend

A078440 Numbers n with property that n is not a power of 2 and the finite sequence n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem contains exactly one prime. (The earliest "1" is meant.)

Table of values

List of values