A205403 - cp's OEIS frontend

A205403 a(n) is the index j < k such that n divides s(k)-s(j) for some j, where s(j) = floor((j+1)^2/2)/2, and k is the least index for which such a j exists.

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

[1, 2, 1, 2, 1, 4, 2, 1, 2, 2, 1, 3, 6, 2, 1, 3, 2, 2, 1, 7, 3, 8, 2, 1, 4, 3, 5, 2, 1, 4, 9, 3, 5, 2, 1, 4, 6, 3, 9, 2, 1, 10, 4, 6, 3, 15, 2, 1, 2, 4, 10, 3, 3, 2, 1, 7, 15, 4, 20, 3, 8, 2, 1, 11, 7, 4, 5, 3, 6, 2, 1, 5, 11, 7, 4, 14, 3, 6, 2, 1]

cp's OEIS Frontend

A205403 a(n) is the index j < k such that n divides s(k)-s(j) for some j, where s(j) = floor((j+1)^2/2)/2, and k is the least index for which such a j exists.

Table of values

List of values

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

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

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