A337490 - cp's OEIS frontend

A337490 a(0)=1; for n > 0, a(n) = the greatest common divisor (GCD) of n and the sum of all previous terms if the GCD is not already in the sequence; otherwise a(n) = a(n-1) + n.

n	a(n)
0	1
1	2
2	4
3	7
4	11
5	5
6	6
7	13
8	21
9	30
10	10
11	21
12	33
13	46
14	14
15	29
16	45
17	62
18	18
19	37
20	57
21	78
22	22
23	45
24	69
25	94
26	26
27	53
28	81
29	110
30	140
31	171
32	203
33	236
34	270
35	305
36	341
37	378
38	416
39	39
40	79
41	120
42	162
43	205
44	249
45	294
46	340
47	387
48	3
49	52
50	102
51	17
52	69
53	122
54	176
55	231
56	287
57	344
58	402
59	461
60	521
61	582
62	644
63	707
64	771
65	836
66	902
67	969

[1, 2, 4, 7, 11, 5, 6, 13, 21, 30, 10, 21, 33, 46, 14, 29, 45, 62, 18, 37, 57, 78, 22, 45, 69, 94, 26, 53, 81, 110, 140, 171, 203, 236, 270, 305, 341, 378, 416, 39, 79, 120, 162, 205, 249, 294, 340, 387, 3, 52, 102, 17, 69, 122, 176, 231, 287, 344, 402, 461, 521, 582, 644, 707, 771, 836, 902, 969]

cp's OEIS Frontend

A337490 a(0)=1; for n > 0, a(n) = the greatest common divisor (GCD) of n and the sum of all previous terms if the GCD is not already in the sequence; otherwise a(n) = a(n-1) + n.

Table of values

List of values

n	a(n)
0	1
1	2
2	4
3	7
4	11
5	5
6	6
7	13
8	21
9	30
10	10
11	21
12	33
13	46
14	14
15	29
16	45
17	62
18	18
19	37
20	57
21	78
22	22
23	45
24	69
25	94
26	26
27	53
28	81
29	110
30	140
31	171
32	203
33	236
34	270
35	305
36	341
37	378
38	416
39	39
40	79
41	120
42	162
43	205
44	249
45	294
46	340
47	387
48	3
49	52
50	102
51	17
52	69
53	122
54	176
55	231
56	287
57	344
58	402
59	461
60	521
61	582
62	644
63	707
64	771
65	836
66	902
67	969

n	a(n)
0	1
1	2
2	4
3	7
4	11
5	5
6	6
7	13
8	21
9	30
10	10
11	21
12	33
13	46
14	14
15	29
16	45
17	62
18	18
19	37
20	57
21	78
22	22
23	45
24	69
25	94
26	26
27	53
28	81
29	110
30	140
31	171
32	203
33	236
34	270
35	305
36	341
37	378
38	416
39	39
40	79
41	120
42	162
43	205
44	249
45	294
46	340
47	387
48	3
49	52
50	102
51	17
52	69
53	122
54	176
55	231
56	287
57	344
58	402
59	461
60	521
61	582
62	644
63	707
64	771
65	836
66	902
67	969

n	a(n)
0	1
1	2
2	4
3	7
4	11
5	5
6	6
7	13
8	21
9	30
10	10
11	21
12	33
13	46
14	14
15	29
16	45
17	62
18	18
19	37
20	57
21	78
22	22
23	45
24	69
25	94
26	26
27	53
28	81
29	110
30	140
31	171
32	203
33	236
34	270
35	305
36	341
37	378
38	416
39	39
40	79
41	120
42	162
43	205
44	249
45	294
46	340
47	387
48	3
49	52
50	102
51	17
52	69
53	122
54	176
55	231
56	287
57	344
58	402
59	461
60	521
61	582
62	644
63	707
64	771
65	836
66	902
67	969