A335382 - cp's OEIS frontend

A335382 a(0) = 0, a(1) = 1; for n > 1, a(n) = a(n-1) - sigma(n) if nonnegative and not already in the sequence, otherwise a(n) = a(n-1) + sigma(n), where sigma(n) is the sum of the divisors of n.

n	a(n)
0	0
1	1
2	4
3	8
4	15
5	9
6	21
7	13
8	28
9	41
10	23
11	11
12	39
13	25
14	49
15	73
16	42
17	24
18	63
19	43
20	85
21	53
22	17
23	41
24	101
25	70
26	112
27	72
28	16
29	46
30	118
31	86
32	149
33	197
34	143
35	95
36	186
37	148
38	88
39	32
40	122
41	80
42	176
43	132
44	48
45	126
46	54
47	6
48	130
49	187
50	94
51	22
52	120
53	66
54	186
55	114
56	234
57	154
58	64
59	124
60	292
61	230
62	134
63	30
64	157
65	241
66	97
67	29
68	155

[0, 1, 4, 8, 15, 9, 21, 13, 28, 41, 23, 11, 39, 25, 49, 73, 42, 24, 63, 43, 85, 53, 17, 41, 101, 70, 112, 72, 16, 46, 118, 86, 149, 197, 143, 95, 186, 148, 88, 32, 122, 80, 176, 132, 48, 126, 54, 6, 130, 187, 94, 22, 120, 66, 186, 114, 234, 154, 64, 124, 292, 230, 134, 30, 157, 241, 97, 29, 155]

cp's OEIS Frontend

A335382 a(0) = 0, a(1) = 1; for n > 1, a(n) = a(n-1) - sigma(n) if nonnegative and not already in the sequence, otherwise a(n) = a(n-1) + sigma(n), where sigma(n) is the sum of the divisors of n.

Table of values

List of values

n	a(n)
0	0
1	1
2	4
3	8
4	15
5	9
6	21
7	13
8	28
9	41
10	23
11	11
12	39
13	25
14	49
15	73
16	42
17	24
18	63
19	43
20	85
21	53
22	17
23	41
24	101
25	70
26	112
27	72
28	16
29	46
30	118
31	86
32	149
33	197
34	143
35	95
36	186
37	148
38	88
39	32
40	122
41	80
42	176
43	132
44	48
45	126
46	54
47	6
48	130
49	187
50	94
51	22
52	120
53	66
54	186
55	114
56	234
57	154
58	64
59	124
60	292
61	230
62	134
63	30
64	157
65	241
66	97
67	29
68	155

n	a(n)
0	0
1	1
2	4
3	8
4	15
5	9
6	21
7	13
8	28
9	41
10	23
11	11
12	39
13	25
14	49
15	73
16	42
17	24
18	63
19	43
20	85
21	53
22	17
23	41
24	101
25	70
26	112
27	72
28	16
29	46
30	118
31	86
32	149
33	197
34	143
35	95
36	186
37	148
38	88
39	32
40	122
41	80
42	176
43	132
44	48
45	126
46	54
47	6
48	130
49	187
50	94
51	22
52	120
53	66
54	186
55	114
56	234
57	154
58	64
59	124
60	292
61	230
62	134
63	30
64	157
65	241
66	97
67	29
68	155

n	a(n)
0	0
1	1
2	4
3	8
4	15
5	9
6	21
7	13
8	28
9	41
10	23
11	11
12	39
13	25
14	49
15	73
16	42
17	24
18	63
19	43
20	85
21	53
22	17
23	41
24	101
25	70
26	112
27	72
28	16
29	46
30	118
31	86
32	149
33	197
34	143
35	95
36	186
37	148
38	88
39	32
40	122
41	80
42	176
43	132
44	48
45	126
46	54
47	6
48	130
49	187
50	94
51	22
52	120
53	66
54	186
55	114
56	234
57	154
58	64
59	124
60	292
61	230
62	134
63	30
64	157
65	241
66	97
67	29
68	155