A259565 - cp's OEIS frontend

A259565 a(1) = 1, for n > 1 a(n) = smallest number not already in the sequence such that the arithmetic mean of two neighboring terms is a squarefree number.

n	a(n)
1	1
2	3
3	7
4	5
5	9
6	11
7	15
8	13
9	17
10	21
11	23
12	19
13	25
14	27
15	31
16	29
17	33
18	35
19	39
20	37
21	41
22	43
23	49
24	45
25	47
26	55
27	51
28	59
29	57
30	53
31	61
32	63
33	67
34	65
35	69
36	71
37	75
38	73
39	81
40	77
41	79
42	85
43	87
44	83
45	89
46	93
47	95
48	91
49	97
50	105
51	99
52	103
53	101
54	109
55	111
56	107
57	113
58	115
59	121
60	117
61	119
62	125
63	129

[1, 3, 7, 5, 9, 11, 15, 13, 17, 21, 23, 19, 25, 27, 31, 29, 33, 35, 39, 37, 41, 43, 49, 45, 47, 55, 51, 59, 57, 53, 61, 63, 67, 65, 69, 71, 75, 73, 81, 77, 79, 85, 87, 83, 89, 93, 95, 91, 97, 105, 99, 103, 101, 109, 111, 107, 113, 115, 121, 117, 119, 125, 129]

cp's OEIS Frontend

A259565 a(1) = 1, for n > 1 a(n) = smallest number not already in the sequence such that the arithmetic mean of two neighboring terms is a squarefree number.

Table of values

List of values

n	a(n)
1	1
2	3
3	7
4	5
5	9
6	11
7	15
8	13
9	17
10	21
11	23
12	19
13	25
14	27
15	31
16	29
17	33
18	35
19	39
20	37
21	41
22	43
23	49
24	45
25	47
26	55
27	51
28	59
29	57
30	53
31	61
32	63
33	67
34	65
35	69
36	71
37	75
38	73
39	81
40	77
41	79
42	85
43	87
44	83
45	89
46	93
47	95
48	91
49	97
50	105
51	99
52	103
53	101
54	109
55	111
56	107
57	113
58	115
59	121
60	117
61	119
62	125
63	129

n	a(n)
1	1
2	3
3	7
4	5
5	9
6	11
7	15
8	13
9	17
10	21
11	23
12	19
13	25
14	27
15	31
16	29
17	33
18	35
19	39
20	37
21	41
22	43
23	49
24	45
25	47
26	55
27	51
28	59
29	57
30	53
31	61
32	63
33	67
34	65
35	69
36	71
37	75
38	73
39	81
40	77
41	79
42	85
43	87
44	83
45	89
46	93
47	95
48	91
49	97
50	105
51	99
52	103
53	101
54	109
55	111
56	107
57	113
58	115
59	121
60	117
61	119
62	125
63	129

n	a(n)
1	1
2	3
3	7
4	5
5	9
6	11
7	15
8	13
9	17
10	21
11	23
12	19
13	25
14	27
15	31
16	29
17	33
18	35
19	39
20	37
21	41
22	43
23	49
24	45
25	47
26	55
27	51
28	59
29	57
30	53
31	61
32	63
33	67
34	65
35	69
36	71
37	75
38	73
39	81
40	77
41	79
42	85
43	87
44	83
45	89
46	93
47	95
48	91
49	97
50	105
51	99
52	103
53	101
54	109
55	111
56	107
57	113
58	115
59	121
60	117
61	119
62	125
63	129