A237523 - cp's OEIS frontend

A237523 a(n) = |{0 < k < n/2: phi(k*(n-k)) + 1 is a square}|, where phi(.) is Euler's totient function.

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

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

cp's OEIS Frontend

A237523 a(n) = |{0 < k < n/2: phi(k*(n-k)) + 1 is a square}|, where phi(.) is Euler's totient function.

Table of values

List of values

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

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

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