A330545 - cp's OEIS frontend

A330545 a(1) = 2; thereafter a(n) = a(n-1) + (-1)^(n + 1)*(prime(n) - prime(n - 1) - 1) (where prime(k) denotes the k-th prime).

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

[2, 2, 3, 2, 5, 4, 7, 6, 9, 4, 5, 0, 3, 2, 5, 0, 5, 4, 9, 6, 7, 2, 5, 0, 7, 4, 5, 2, 3, 0, 13, 10, 15, 14, 23, 22, 27, 22, 25, 20, 25, 24, 33, 32, 35, 34, 45, 34, 37, 36, 39, 34, 35, 26, 31, 26, 31, 30, 35, 32, 33, 24, 37, 34, 35, 32, 45, 40, 49, 48, 51, 46, 53, 48, 53, 50, 55, 48, 51, 44, 53]

cp's OEIS Frontend

A330545 a(1) = 2; thereafter a(n) = a(n-1) + (-1)^(n + 1)*(prime(n) - prime(n - 1) - 1) (where prime(k) denotes the k-th prime).

Table of values

List of values

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

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

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