A138508 - cp's OEIS frontend

A138508 Semiprime analog of Riesel problem: start with n; repeatedly double and add 1 until reach a semiprime. Sequence gives number of steps to reach a semiprime or 0 if no semiprime is ever reached.

n	a(n)
1	3
2	5
3	2
4	1
5	4
6	3
7	1
8	2
9	2
10	1
11	3
12	1
13	2
14	3
15	5
16	1
17	1
18	4
19	1
20	4
21	2
22	2
23	2
24	1
25	1
26	3
27	1
28	1
29	2
30	2
31	4
32	1
33	4
34	1
35	2
36	3
37	3
38	1
39	2
40	3
41	3
42	1
43	1
44	7
45	1
46	1
47	1
48	3
49	4
50	2
51	3
52	10
53	2
54	2
55	1
56	6
57	1
58	2
59	1
60	1
61	1
62	4
63	3
64	1
65	3
66	1
67	3
68	3
69	3
70	1
71	1
72	1
73	2
74	2
75	2
76	5
77	1
78	4
79	1
80	1
81	2
82	6
83	2
84	1
85	3
86	3
87	3
88	1
89	6
90	5
91	1
92	1
93	1
94	5
95	3
96	5
97	2
98	2
99	3
100	1
101	1
102	1
103	2
104	1
105	9
106	1
107	1
108	1
109	1
110	1
111	2

[3, 5, 2, 1, 4, 3, 1, 2, 2, 1, 3, 1, 2, 3, 5, 1, 1, 4, 1, 4, 2, 2, 2, 1, 1, 3, 1, 1, 2, 2, 4, 1, 4, 1, 2, 3, 3, 1, 2, 3, 3, 1, 1, 7, 1, 1, 1, 3, 4, 2, 3, 10, 2, 2, 1, 6, 1, 2, 1, 1, 1, 4, 3, 1, 3, 1, 3, 3, 3, 1, 1, 1, 2, 2, 2, 5, 1, 4, 1, 1, 2, 6, 2, 1, 3, 3, 3, 1, 6, 5, 1, 1, 1, 5, 3, 5, 2, 2, 3, 1, 1, 1, 2, 1, 9, 1, 1, 1, 1, 1, 2]

cp's OEIS Frontend

A138508 Semiprime analog of Riesel problem: start with n; repeatedly double and add 1 until reach a semiprime. Sequence gives number of steps to reach a semiprime or 0 if no semiprime is ever reached.

Table of values

List of values

n	a(n)
1	3
2	5
3	2
4	1
5	4
6	3
7	1
8	2
9	2
10	1
11	3
12	1
13	2
14	3
15	5
16	1
17	1
18	4
19	1
20	4
21	2
22	2
23	2
24	1
25	1
26	3
27	1
28	1
29	2
30	2
31	4
32	1
33	4
34	1
35	2
36	3
37	3
38	1
39	2
40	3
41	3
42	1
43	1
44	7
45	1
46	1
47	1
48	3
49	4
50	2
51	3
52	10
53	2
54	2
55	1
56	6
57	1
58	2
59	1
60	1
61	1
62	4
63	3
64	1
65	3
66	1
67	3
68	3
69	3
70	1
71	1
72	1
73	2
74	2
75	2
76	5
77	1
78	4
79	1
80	1
81	2
82	6
83	2
84	1
85	3
86	3
87	3
88	1
89	6
90	5
91	1
92	1
93	1
94	5
95	3
96	5
97	2
98	2
99	3
100	1
101	1
102	1
103	2
104	1
105	9
106	1
107	1
108	1
109	1
110	1
111	2

n	a(n)
1	3
2	5
3	2
4	1
5	4
6	3
7	1
8	2
9	2
10	1
11	3
12	1
13	2
14	3
15	5
16	1
17	1
18	4
19	1
20	4
21	2
22	2
23	2
24	1
25	1
26	3
27	1
28	1
29	2
30	2
31	4
32	1
33	4
34	1
35	2
36	3
37	3
38	1
39	2
40	3
41	3
42	1
43	1
44	7
45	1
46	1
47	1
48	3
49	4
50	2
51	3
52	10
53	2
54	2
55	1
56	6
57	1
58	2
59	1
60	1
61	1
62	4
63	3
64	1
65	3
66	1
67	3
68	3
69	3
70	1
71	1
72	1
73	2
74	2
75	2
76	5
77	1
78	4
79	1
80	1
81	2
82	6
83	2
84	1
85	3
86	3
87	3
88	1
89	6
90	5
91	1
92	1
93	1
94	5
95	3
96	5
97	2
98	2
99	3
100	1
101	1
102	1
103	2
104	1
105	9
106	1
107	1
108	1
109	1
110	1
111	2

n	a(n)
1	3
2	5
3	2
4	1
5	4
6	3
7	1
8	2
9	2
10	1
11	3
12	1
13	2
14	3
15	5
16	1
17	1
18	4
19	1
20	4
21	2
22	2
23	2
24	1
25	1
26	3
27	1
28	1
29	2
30	2
31	4
32	1
33	4
34	1
35	2
36	3
37	3
38	1
39	2
40	3
41	3
42	1
43	1
44	7
45	1
46	1
47	1
48	3
49	4
50	2
51	3
52	10
53	2
54	2
55	1
56	6
57	1
58	2
59	1
60	1
61	1
62	4
63	3
64	1
65	3
66	1
67	3
68	3
69	3
70	1
71	1
72	1
73	2
74	2
75	2
76	5
77	1
78	4
79	1
80	1
81	2
82	6
83	2
84	1
85	3
86	3
87	3
88	1
89	6
90	5
91	1
92	1
93	1
94	5
95	3
96	5
97	2
98	2
99	3
100	1
101	1
102	1
103	2
104	1
105	9
106	1
107	1
108	1
109	1
110	1
111	2