A309892 - cp's OEIS frontend

A309892 a(0) = 0, a(1) = 1, and for any n > 1, a(n) is the number of iterations of the map x -> x - gpf(x) (where gpf(x) denotes the greatest prime factor of x) required to reach 0 starting from n.

n	a(n)
0	0
1	1
2	1
3	1
4	2
5	1
6	2
7	1
8	3
9	3
10	2
11	1
12	4
13	1
14	2
15	3
16	3
17	1
18	4
19	1
20	4
21	3
22	2
23	1
24	4
25	5
26	2
27	5
28	4
29	1
30	6
31	1
32	7
33	3
34	2
35	5
36	4
37	1
38	2
39	3
40	6
41	1
42	6
43	1
44	4
45	7
46	2
47	1
48	8
49	7
50	8
51	3
52	4
53	1
54	4
55	5
56	8
57	3
58	2
59	1
60	6
61	1
62	2
63	9
64	3
65	5
66	6
67	1
68	4
69	3
70	10
71	1
72	4
73	1
74	2
75	11
76	4
77	7
78	6
79	1
80	12
81	7
82	2
83	1
84	8
85	5

[0, 1, 1, 1, 2, 1, 2, 1, 3, 3, 2, 1, 4, 1, 2, 3, 3, 1, 4, 1, 4, 3, 2, 1, 4, 5, 2, 5, 4, 1, 6, 1, 7, 3, 2, 5, 4, 1, 2, 3, 6, 1, 6, 1, 4, 7, 2, 1, 8, 7, 8, 3, 4, 1, 4, 5, 8, 3, 2, 1, 6, 1, 2, 9, 3, 5, 6, 1, 4, 3, 10, 1, 4, 1, 2, 11, 4, 7, 6, 1, 12, 7, 2, 1, 8, 5]

cp's OEIS Frontend

A309892 a(0) = 0, a(1) = 1, and for any n > 1, a(n) is the number of iterations of the map x -> x - gpf(x) (where gpf(x) denotes the greatest prime factor of x) required to reach 0 starting from n.

Table of values

List of values

n	a(n)
0	0
1	1
2	1
3	1
4	2
5	1
6	2
7	1
8	3
9	3
10	2
11	1
12	4
13	1
14	2
15	3
16	3
17	1
18	4
19	1
20	4
21	3
22	2
23	1
24	4
25	5
26	2
27	5
28	4
29	1
30	6
31	1
32	7
33	3
34	2
35	5
36	4
37	1
38	2
39	3
40	6
41	1
42	6
43	1
44	4
45	7
46	2
47	1
48	8
49	7
50	8
51	3
52	4
53	1
54	4
55	5
56	8
57	3
58	2
59	1
60	6
61	1
62	2
63	9
64	3
65	5
66	6
67	1
68	4
69	3
70	10
71	1
72	4
73	1
74	2
75	11
76	4
77	7
78	6
79	1
80	12
81	7
82	2
83	1
84	8
85	5

n	a(n)
0	0
1	1
2	1
3	1
4	2
5	1
6	2
7	1
8	3
9	3
10	2
11	1
12	4
13	1
14	2
15	3
16	3
17	1
18	4
19	1
20	4
21	3
22	2
23	1
24	4
25	5
26	2
27	5
28	4
29	1
30	6
31	1
32	7
33	3
34	2
35	5
36	4
37	1
38	2
39	3
40	6
41	1
42	6
43	1
44	4
45	7
46	2
47	1
48	8
49	7
50	8
51	3
52	4
53	1
54	4
55	5
56	8
57	3
58	2
59	1
60	6
61	1
62	2
63	9
64	3
65	5
66	6
67	1
68	4
69	3
70	10
71	1
72	4
73	1
74	2
75	11
76	4
77	7
78	6
79	1
80	12
81	7
82	2
83	1
84	8
85	5

n	a(n)
0	0
1	1
2	1
3	1
4	2
5	1
6	2
7	1
8	3
9	3
10	2
11	1
12	4
13	1
14	2
15	3
16	3
17	1
18	4
19	1
20	4
21	3
22	2
23	1
24	4
25	5
26	2
27	5
28	4
29	1
30	6
31	1
32	7
33	3
34	2
35	5
36	4
37	1
38	2
39	3
40	6
41	1
42	6
43	1
44	4
45	7
46	2
47	1
48	8
49	7
50	8
51	3
52	4
53	1
54	4
55	5
56	8
57	3
58	2
59	1
60	6
61	1
62	2
63	9
64	3
65	5
66	6
67	1
68	4
69	3
70	10
71	1
72	4
73	1
74	2
75	11
76	4
77	7
78	6
79	1
80	12
81	7
82	2
83	1
84	8
85	5