A330547 - cp's OEIS frontend

A330547 a(1)=2; thereafter a(n) = a(n-1) + (-1)^(n+1)*(prime(n)-prime(n-1)) (where prime(k) denotes the k-th prime).

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

[2, 1, 3, 1, 5, 3, 7, 5, 9, 3, 5, -1, 3, 1, 5, -1, 5, 3, 9, 5, 7, 1, 5, -1, 7, 3, 5, 1, 3, -1, 13, 9, 15, 13, 23, 21, 27, 21, 25, 19, 25, 23, 33, 31, 35, 33, 45, 33, 37, 35, 39, 33, 35, 25, 31, 25, 31, 29, 35, 31, 33, 23, 37, 33, 35, 31, 45, 39, 49, 47, 51, 45, 53, 47, 53, 49, 55, 47, 51, 43, 53, 51, 61, 59, 65, 61]

cp's OEIS Frontend

A330547 a(1)=2; thereafter a(n) = a(n-1) + (-1)^(n+1)*(prime(n)-prime(n-1)) (where prime(k) denotes the k-th prime).

Table of values

List of values

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

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

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