A147844 - cp's OEIS frontend

A147844 Difference between the number of distinct prime divisors of (2n)!/n!^2 and pi(2n), where pi(x) is the prime counting function.

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

[0, 0, 1, 1, 1, 1, 2, 1, 2, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 2, 3, 4, 5, 5, 5, 5, 6, 4, 3, 5, 6, 5, 4, 5, 5, 6, 7, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 6, 7, 7, 8, 9, 8, 8, 10, 10, 11, 10, 10, 9, 9, 9, 9, 9, 9, 9, 8, 9, 10, 11, 11, 10, 10, 10, 10, 11, 10, 10, 11, 10, 10, 11, 11, 12, 12, 11, 12, 12, 12, 13, 13]

cp's OEIS Frontend

A147844 Difference between the number of distinct prime divisors of (2n)!/n!^2 and pi(2n), where pi(x) is the prime counting function.

Table of values

List of values

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

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

cp's OEIS Frontend

A147844 Difference between the number of distinct prime divisors of (2*n)!/n!^2 and pi(2*n), where pi(x) is the prime counting function.

Table of values

List of values

A147844 Difference between the number of distinct prime divisors of (2n)!/n!^2 and pi(2n), where pi(x) is the prime counting function.

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