A093903 - cp's OEIS frontend

A093903 a(1) = 1; for n > 1, a(n) = a(n-1)-p if there exists a prime p (take the smallest) that has not yet been used and is such that a(n) is new and > 0, otherwise a(n) = a(n-1)+p if the same conditions are satisfied.

n	a(n)
1	1
2	3
3	6
4	11
5	4
6	15
7	2
8	19
9	38
10	9
11	32
12	63
13	26
14	67
15	24
16	71
17	18
18	77
19	16
20	83
21	12
22	85
23	164
24	81
25	170
26	73
27	174
28	65
29	168
30	61
31	188
32	75
33	206
34	69
35	208
36	59
37	210
38	53
39	216
40	49
41	222
42	43
43	224
44	33
45	226
46	29
47	228
48	17
49	240
50	13
51	242
52	475
53	236
54	477
55	220
56	471
57	202
58	465
59	194
60	487
61	204
62	481
63	200

[1, 3, 6, 11, 4, 15, 2, 19, 38, 9, 32, 63, 26, 67, 24, 71, 18, 77, 16, 83, 12, 85, 164, 81, 170, 73, 174, 65, 168, 61, 188, 75, 206, 69, 208, 59, 210, 53, 216, 49, 222, 43, 224, 33, 226, 29, 228, 17, 240, 13, 242, 475, 236, 477, 220, 471, 202, 465, 194, 487, 204, 481, 200]

cp's OEIS Frontend

A093903 a(1) = 1; for n > 1, a(n) = a(n-1)-p if there exists a prime p (take the smallest) that has not yet been used and is such that a(n) is new and > 0, otherwise a(n) = a(n-1)+p if the same conditions are satisfied.

Table of values

List of values

n	a(n)
1	1
2	3
3	6
4	11
5	4
6	15
7	2
8	19
9	38
10	9
11	32
12	63
13	26
14	67
15	24
16	71
17	18
18	77
19	16
20	83
21	12
22	85
23	164
24	81
25	170
26	73
27	174
28	65
29	168
30	61
31	188
32	75
33	206
34	69
35	208
36	59
37	210
38	53
39	216
40	49
41	222
42	43
43	224
44	33
45	226
46	29
47	228
48	17
49	240
50	13
51	242
52	475
53	236
54	477
55	220
56	471
57	202
58	465
59	194
60	487
61	204
62	481
63	200

n	a(n)
1	1
2	3
3	6
4	11
5	4
6	15
7	2
8	19
9	38
10	9
11	32
12	63
13	26
14	67
15	24
16	71
17	18
18	77
19	16
20	83
21	12
22	85
23	164
24	81
25	170
26	73
27	174
28	65
29	168
30	61
31	188
32	75
33	206
34	69
35	208
36	59
37	210
38	53
39	216
40	49
41	222
42	43
43	224
44	33
45	226
46	29
47	228
48	17
49	240
50	13
51	242
52	475
53	236
54	477
55	220
56	471
57	202
58	465
59	194
60	487
61	204
62	481
63	200

n	a(n)
1	1
2	3
3	6
4	11
5	4
6	15
7	2
8	19
9	38
10	9
11	32
12	63
13	26
14	67
15	24
16	71
17	18
18	77
19	16
20	83
21	12
22	85
23	164
24	81
25	170
26	73
27	174
28	65
29	168
30	61
31	188
32	75
33	206
34	69
35	208
36	59
37	210
38	53
39	216
40	49
41	222
42	43
43	224
44	33
45	226
46	29
47	228
48	17
49	240
50	13
51	242
52	475
53	236
54	477
55	220
56	471
57	202
58	465
59	194
60	487
61	204
62	481
63	200