A071854 - cp's OEIS frontend

A071854 a(n) = (number of distinct prime factors in C(2n,n)) - pi(n).

n	a(n)
1	1
2	1
3	0
4	1
5	0
6	1
7	0
8	1
9	1
10	1
11	1
12	1
13	0
14	0
15	1
16	2
17	1
18	2
19	1
20	2
21	2
22	2
23	0
24	1
25	1
26	1
27	1
28	3
29	3
30	2
31	1
32	2
33	3
34	3
35	3
36	3
37	2
38	3
39	2
40	3
41	2
42	3
43	2
44	2
45	3
46	3
47	2
48	3
49	3
50	3
51	3
52	3
53	3
54	4
55	3
56	3
57	3
58	4
59	3
60	4
61	3
62	3
63	3
64	4
65	4
66	5
67	5
68	4
69	4
70	4
71	3
72	4
73	3
74	3
75	4
76	4
77	5
78	5
79	4
80	5
81	5
82	5
83	4
84	4
85	4
86	5
87	5
88	5
89	4
90	4
91	5
92	6
93	5
94	5
95	5
96	6
97	5
98	4
99	5
100	6
101	5
102	6
103	5
104	6
105	6

[1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 2, 1, 2, 1, 2, 2, 2, 0, 1, 1, 1, 1, 3, 3, 2, 1, 2, 3, 3, 3, 3, 2, 3, 2, 3, 2, 3, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 4, 3, 4, 3, 3, 3, 4, 4, 5, 5, 4, 4, 4, 3, 4, 3, 3, 4, 4, 5, 5, 4, 5, 5, 5, 4, 4, 4, 5, 5, 5, 4, 4, 5, 6, 5, 5, 5, 6, 5, 4, 5, 6, 5, 6, 5, 6, 6]

cp's OEIS Frontend

A071854 a(n) = (number of distinct prime factors in C(2n,n)) - pi(n).

Table of values

List of values

n	a(n)
1	1
2	1
3	0
4	1
5	0
6	1
7	0
8	1
9	1
10	1
11	1
12	1
13	0
14	0
15	1
16	2
17	1
18	2
19	1
20	2
21	2
22	2
23	0
24	1
25	1
26	1
27	1
28	3
29	3
30	2
31	1
32	2
33	3
34	3
35	3
36	3
37	2
38	3
39	2
40	3
41	2
42	3
43	2
44	2
45	3
46	3
47	2
48	3
49	3
50	3
51	3
52	3
53	3
54	4
55	3
56	3
57	3
58	4
59	3
60	4
61	3
62	3
63	3
64	4
65	4
66	5
67	5
68	4
69	4
70	4
71	3
72	4
73	3
74	3
75	4
76	4
77	5
78	5
79	4
80	5
81	5
82	5
83	4
84	4
85	4
86	5
87	5
88	5
89	4
90	4
91	5
92	6
93	5
94	5
95	5
96	6
97	5
98	4
99	5
100	6
101	5
102	6
103	5
104	6
105	6

n	a(n)
1	1
2	1
3	0
4	1
5	0
6	1
7	0
8	1
9	1
10	1
11	1
12	1
13	0
14	0
15	1
16	2
17	1
18	2
19	1
20	2
21	2
22	2
23	0
24	1
25	1
26	1
27	1
28	3
29	3
30	2
31	1
32	2
33	3
34	3
35	3
36	3
37	2
38	3
39	2
40	3
41	2
42	3
43	2
44	2
45	3
46	3
47	2
48	3
49	3
50	3
51	3
52	3
53	3
54	4
55	3
56	3
57	3
58	4
59	3
60	4
61	3
62	3
63	3
64	4
65	4
66	5
67	5
68	4
69	4
70	4
71	3
72	4
73	3
74	3
75	4
76	4
77	5
78	5
79	4
80	5
81	5
82	5
83	4
84	4
85	4
86	5
87	5
88	5
89	4
90	4
91	5
92	6
93	5
94	5
95	5
96	6
97	5
98	4
99	5
100	6
101	5
102	6
103	5
104	6
105	6

n	a(n)
1	1
2	1
3	0
4	1
5	0
6	1
7	0
8	1
9	1
10	1
11	1
12	1
13	0
14	0
15	1
16	2
17	1
18	2
19	1
20	2
21	2
22	2
23	0
24	1
25	1
26	1
27	1
28	3
29	3
30	2
31	1
32	2
33	3
34	3
35	3
36	3
37	2
38	3
39	2
40	3
41	2
42	3
43	2
44	2
45	3
46	3
47	2
48	3
49	3
50	3
51	3
52	3
53	3
54	4
55	3
56	3
57	3
58	4
59	3
60	4
61	3
62	3
63	3
64	4
65	4
66	5
67	5
68	4
69	4
70	4
71	3
72	4
73	3
74	3
75	4
76	4
77	5
78	5
79	4
80	5
81	5
82	5
83	4
84	4
85	4
86	5
87	5
88	5
89	4
90	4
91	5
92	6
93	5
94	5
95	5
96	6
97	5
98	4
99	5
100	6
101	5
102	6
103	5
104	6
105	6