A068319 - cp's OEIS frontend

A068319 a(n) = if n <= lpf(n)^2 then lpf(n) else a(lpf(n) + n/lpf(n)), where lpf = least prime factor, A020639.

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

[1, 2, 3, 2, 5, 5, 7, 5, 3, 7, 11, 5, 13, 3, 5, 7, 17, 11, 19, 5, 7, 13, 23, 3, 5, 5, 5, 7, 29, 17, 31, 11, 3, 19, 5, 5, 37, 7, 7, 13, 41, 23, 43, 3, 11, 5, 47, 5, 7, 5, 5, 7, 53, 29, 7, 17, 13, 31, 59, 11, 61, 3, 3, 19, 11, 5, 67, 5, 5, 37, 71, 7, 73, 7]

cp's OEIS Frontend

A068319 a(n) = if n <= lpf(n)^2 then lpf(n) else a(lpf(n) + n/lpf(n)), where lpf = least prime factor, A020639.

Table of values

List of values

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

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

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