A260643 - cp's OEIS frontend

A260643 Start a spiral of numbers on a square grid, with the initial square as a(1) = 1. a(n) is the smallest positive integer not equal to or previously adjacent (horizontally/vertically) to its neighbors. See the Comments section for a more exact definition.

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

[1, 2, 3, 4, 2, 5, 3, 6, 7, 1, 8, 7, 4, 8, 5, 6, 4, 9, 7, 10, 1, 9, 8, 11, 3, 12, 11, 10, 12, 13, 1, 12, 14, 9, 10, 14, 1, 15, 6, 13, 2, 16, 3, 17, 11, 13, 5, 14, 2, 11, 6, 14, 13, 9, 15, 18, 2, 19, 5, 15, 16, 4, 17, 20, 2, 21, 3, 18, 16, 17, 5, 20, 4, 19, 6]

cp's OEIS Frontend

A260643 Start a spiral of numbers on a square grid, with the initial square as a(1) = 1. a(n) is the smallest positive integer not equal to or previously adjacent (horizontally/vertically) to its neighbors. See the Comments section for a more exact definition.

Table of values

List of values

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

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

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