A236998 - cp's OEIS frontend

A236998 a(n) = |{0 < k < n/2: phi(k)*phi(n-k) is a square}|, where phi(.) is Euler's totient function.

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

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

cp's OEIS Frontend

A236998 a(n) = |{0 < k < n/2: phi(k)*phi(n-k) is a square}|, where phi(.) is Euler's totient function.

Table of values

List of values

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

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

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