A348673 - cp's OEIS frontend

A348673 The numbers visited on a square spiral when stepping to the closest unvisited number such that the sum of that number and the current number is composite. If two or more such numbers exist then the smallest is chosen.

n	a(n)
1	1
2	8
3	7
4	20
5	19
6	6
7	4
8	5
9	16
10	17
11	18
12	39
13	38
14	37
15	63
16	36
17	62
18	61
19	34
20	15
21	3
22	12
23	13
24	14
25	32
26	31
27	56
28	55
29	30
30	54
31	87
32	88
33	89
34	130
35	129
36	177
37	128
38	127
39	86
40	85
41	84
42	51
43	26
44	25
45	10
46	11
47	28
48	27
49	53
50	52
51	50
52	49
53	80
54	79
55	47
56	46
57	23
58	22
59	44
60	21
61	42
62	43
63	72
64	71
65	70
66	41
67	40
68	68
69	67
70	66
71	103
72	102

[1, 8, 7, 20, 19, 6, 4, 5, 16, 17, 18, 39, 38, 37, 63, 36, 62, 61, 34, 15, 3, 12, 13, 14, 32, 31, 56, 55, 30, 54, 87, 88, 89, 130, 129, 177, 128, 127, 86, 85, 84, 51, 26, 25, 10, 11, 28, 27, 53, 52, 50, 49, 80, 79, 47, 46, 23, 22, 44, 21, 42, 43, 72, 71, 70, 41, 40, 68, 67, 66, 103, 102]

cp's OEIS Frontend

A348673 The numbers visited on a square spiral when stepping to the closest unvisited number such that the sum of that number and the current number is composite. If two or more such numbers exist then the smallest is chosen.

Table of values

List of values

n	a(n)
1	1
2	8
3	7
4	20
5	19
6	6
7	4
8	5
9	16
10	17
11	18
12	39
13	38
14	37
15	63
16	36
17	62
18	61
19	34
20	15
21	3
22	12
23	13
24	14
25	32
26	31
27	56
28	55
29	30
30	54
31	87
32	88
33	89
34	130
35	129
36	177
37	128
38	127
39	86
40	85
41	84
42	51
43	26
44	25
45	10
46	11
47	28
48	27
49	53
50	52
51	50
52	49
53	80
54	79
55	47
56	46
57	23
58	22
59	44
60	21
61	42
62	43
63	72
64	71
65	70
66	41
67	40
68	68
69	67
70	66
71	103
72	102

n	a(n)
1	1
2	8
3	7
4	20
5	19
6	6
7	4
8	5
9	16
10	17
11	18
12	39
13	38
14	37
15	63
16	36
17	62
18	61
19	34
20	15
21	3
22	12
23	13
24	14
25	32
26	31
27	56
28	55
29	30
30	54
31	87
32	88
33	89
34	130
35	129
36	177
37	128
38	127
39	86
40	85
41	84
42	51
43	26
44	25
45	10
46	11
47	28
48	27
49	53
50	52
51	50
52	49
53	80
54	79
55	47
56	46
57	23
58	22
59	44
60	21
61	42
62	43
63	72
64	71
65	70
66	41
67	40
68	68
69	67
70	66
71	103
72	102

n	a(n)
1	1
2	8
3	7
4	20
5	19
6	6
7	4
8	5
9	16
10	17
11	18
12	39
13	38
14	37
15	63
16	36
17	62
18	61
19	34
20	15
21	3
22	12
23	13
24	14
25	32
26	31
27	56
28	55
29	30
30	54
31	87
32	88
33	89
34	130
35	129
36	177
37	128
38	127
39	86
40	85
41	84
42	51
43	26
44	25
45	10
46	11
47	28
48	27
49	53
50	52
51	50
52	49
53	80
54	79
55	47
56	46
57	23
58	22
59	44
60	21
61	42
62	43
63	72
64	71
65	70
66	41
67	40
68	68
69	67
70	66
71	103
72	102