A249738 - cp's OEIS frontend

A249738 a(n) = 0 if n is 1 or a prime, otherwise, when n = A020639(n) * A032742(n), a(n) = the largest k < A032742(n) such that either k = 1 or A020639(k) >= A020639(n), where A020639(n) and A032742(n) are the smallest prime and the largest proper divisor dividing n.

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

[0, 0, 0, 1, 0, 2, 0, 3, 1, 4, 0, 5, 0, 6, 3, 7, 0, 8, 0, 9, 5, 10, 0, 11, 1, 12, 7, 13, 0, 14, 0, 15, 9, 16, 5, 17, 0, 18, 11, 19, 0, 20, 0, 21, 13, 22, 0, 23, 1, 24, 15, 25, 0, 26, 7, 27, 17, 28, 0, 29, 0, 30, 19, 31, 11, 32, 0, 33, 21, 34, 0, 35, 0, 36, 23, 37, 7, 38, 0, 39, 25, 40, 0, 41, 13, 42, 27, 43, 0, 44, 11, 45, 29, 46, 17, 47, 0, 48, 31, 49, 0, 50]

cp's OEIS Frontend

A249738 a(n) = 0 if n is 1 or a prime, otherwise, when n = A020639(n) * A032742(n), a(n) = the largest k < A032742(n) such that either k = 1 or A020639(k) >= A020639(n), where A020639(n) and A032742(n) are the smallest prime and the largest proper divisor dividing 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	3
9	1
10	4
11	0
12	5
13	0
14	6
15	3
16	7
17	0
18	8
19	0
20	9
21	5
22	10
23	0
24	11
25	1
26	12
27	7
28	13
29	0
30	14
31	0
32	15
33	9
34	16
35	5
36	17
37	0
38	18
39	11
40	19
41	0
42	20
43	0
44	21
45	13
46	22
47	0
48	23
49	1
50	24
51	15
52	25
53	0
54	26
55	7
56	27
57	17
58	28
59	0
60	29
61	0
62	30
63	19
64	31
65	11
66	32
67	0
68	33
69	21
70	34
71	0
72	35
73	0
74	36
75	23
76	37
77	7
78	38
79	0
80	39
81	25
82	40
83	0
84	41
85	13
86	42
87	27
88	43
89	0
90	44
91	11
92	45
93	29
94	46
95	17
96	47
97	0
98	48
99	31
100	49
101	0
102	50

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

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