A286471 - cp's OEIS frontend

A286471 If n is noncomposite, then a(n) = 0, otherwise 1 + difference between indices of the two smallest (not necessarily distinct) prime factors of n.

n	a(n)
1	0
2	0
3	0
4	1
5	0
6	2
7	0
8	1
9	1
10	3
11	0
12	1
13	0
14	4
15	2
16	1
17	0
18	2
19	0
20	1
21	3
22	5
23	0
24	1
25	1
26	6
27	1
28	1
29	0
30	2
31	0
32	1
33	4
34	7
35	2
36	1
37	0
38	8
39	5
40	1
41	0
42	2
43	0
44	1
45	1
46	9
47	0
48	1
49	1
50	3
51	6
52	1
53	0
54	2
55	3
56	1
57	7
58	10
59	0
60	1
61	0
62	11
63	1
64	1
65	4
66	2
67	0
68	1
69	8
70	3
71	0
72	1
73	0
74	12
75	2
76	1
77	2
78	2
79	0
80	1
81	1
82	13
83	0
84	1
85	5
86	14
87	9
88	1
89	0
90	2
91	3
92	1
93	10
94	15
95	6
96	1
97	0
98	4
99	1
100	1
101	0
102	2
103	0
104	1
105	2
106	16
107	0
108	1
109	0
110	3
111	11
112	1
113	0
114	2
115	7
116	1
117	1
118	17

[0, 0, 0, 1, 0, 2, 0, 1, 1, 3, 0, 1, 0, 4, 2, 1, 0, 2, 0, 1, 3, 5, 0, 1, 1, 6, 1, 1, 0, 2, 0, 1, 4, 7, 2, 1, 0, 8, 5, 1, 0, 2, 0, 1, 1, 9, 0, 1, 1, 3, 6, 1, 0, 2, 3, 1, 7, 10, 0, 1, 0, 11, 1, 1, 4, 2, 0, 1, 8, 3, 0, 1, 0, 12, 2, 1, 2, 2, 0, 1, 1, 13, 0, 1, 5, 14, 9, 1, 0, 2, 3, 1, 10, 15, 6, 1, 0, 4, 1, 1, 0, 2, 0, 1, 2, 16, 0, 1, 0, 3, 11, 1, 0, 2, 7, 1, 1, 17]

cp's OEIS Frontend

A286471 If n is noncomposite, then a(n) = 0, otherwise 1 + difference between indices of the two smallest (not necessarily distinct) prime factors of n.

Table of values

List of values

n	a(n)
1	0
2	0
3	0
4	1
5	0
6	2
7	0
8	1
9	1
10	3
11	0
12	1
13	0
14	4
15	2
16	1
17	0
18	2
19	0
20	1
21	3
22	5
23	0
24	1
25	1
26	6
27	1
28	1
29	0
30	2
31	0
32	1
33	4
34	7
35	2
36	1
37	0
38	8
39	5
40	1
41	0
42	2
43	0
44	1
45	1
46	9
47	0
48	1
49	1
50	3
51	6
52	1
53	0
54	2
55	3
56	1
57	7
58	10
59	0
60	1
61	0
62	11
63	1
64	1
65	4
66	2
67	0
68	1
69	8
70	3
71	0
72	1
73	0
74	12
75	2
76	1
77	2
78	2
79	0
80	1
81	1
82	13
83	0
84	1
85	5
86	14
87	9
88	1
89	0
90	2
91	3
92	1
93	10
94	15
95	6
96	1
97	0
98	4
99	1
100	1
101	0
102	2
103	0
104	1
105	2
106	16
107	0
108	1
109	0
110	3
111	11
112	1
113	0
114	2
115	7
116	1
117	1
118	17

n	a(n)
1	0
2	0
3	0
4	1
5	0
6	2
7	0
8	1
9	1
10	3
11	0
12	1
13	0
14	4
15	2
16	1
17	0
18	2
19	0
20	1
21	3
22	5
23	0
24	1
25	1
26	6
27	1
28	1
29	0
30	2
31	0
32	1
33	4
34	7
35	2
36	1
37	0
38	8
39	5
40	1
41	0
42	2
43	0
44	1
45	1
46	9
47	0
48	1
49	1
50	3
51	6
52	1
53	0
54	2
55	3
56	1
57	7
58	10
59	0
60	1
61	0
62	11
63	1
64	1
65	4
66	2
67	0
68	1
69	8
70	3
71	0
72	1
73	0
74	12
75	2
76	1
77	2
78	2
79	0
80	1
81	1
82	13
83	0
84	1
85	5
86	14
87	9
88	1
89	0
90	2
91	3
92	1
93	10
94	15
95	6
96	1
97	0
98	4
99	1
100	1
101	0
102	2
103	0
104	1
105	2
106	16
107	0
108	1
109	0
110	3
111	11
112	1
113	0
114	2
115	7
116	1
117	1
118	17

n	a(n)
1	0
2	0
3	0
4	1
5	0
6	2
7	0
8	1
9	1
10	3
11	0
12	1
13	0
14	4
15	2
16	1
17	0
18	2
19	0
20	1
21	3
22	5
23	0
24	1
25	1
26	6
27	1
28	1
29	0
30	2
31	0
32	1
33	4
34	7
35	2
36	1
37	0
38	8
39	5
40	1
41	0
42	2
43	0
44	1
45	1
46	9
47	0
48	1
49	1
50	3
51	6
52	1
53	0
54	2
55	3
56	1
57	7
58	10
59	0
60	1
61	0
62	11
63	1
64	1
65	4
66	2
67	0
68	1
69	8
70	3
71	0
72	1
73	0
74	12
75	2
76	1
77	2
78	2
79	0
80	1
81	1
82	13
83	0
84	1
85	5
86	14
87	9
88	1
89	0
90	2
91	3
92	1
93	10
94	15
95	6
96	1
97	0
98	4
99	1
100	1
101	0
102	2
103	0
104	1
105	2
106	16
107	0
108	1
109	0
110	3
111	11
112	1
113	0
114	2
115	7
116	1
117	1
118	17