A081943 - cp's OEIS frontend

A081943 a(1) = 1, a(n)= smallest number not occurring earlier such that a(n-1)*a(n) -1 is a prime. re-arrangement of natural numbers such that the product of adjacent terms is one more than a prime.

n	a(n)
1	1
2	3
3	2
4	4
5	5
6	6
7	7
8	12
9	9
10	8
11	10
12	11
13	18
14	13
15	14
16	16
17	15
18	24
19	20
20	19
21	30
22	17
23	22
24	21
25	28
26	23
27	36
28	27
29	26
30	33
31	40
32	32
33	31
34	42
35	25
36	50
37	34
38	38
39	39
40	48
41	43
42	60
43	35
44	46
45	45
46	44
47	37
48	54
49	41
50	52
51	57
52	56
53	55
54	68
55	49
56	62
57	64
58	53
59	70
60	29
61	66
62	63
63	76
64	47
65	82
66	69
67	58
68	51
69	72
70	61

[1, 3, 2, 4, 5, 6, 7, 12, 9, 8, 10, 11, 18, 13, 14, 16, 15, 24, 20, 19, 30, 17, 22, 21, 28, 23, 36, 27, 26, 33, 40, 32, 31, 42, 25, 50, 34, 38, 39, 48, 43, 60, 35, 46, 45, 44, 37, 54, 41, 52, 57, 56, 55, 68, 49, 62, 64, 53, 70, 29, 66, 63, 76, 47, 82, 69, 58, 51, 72, 61]

cp's OEIS Frontend

A081943 a(1) = 1, a(n)= smallest number not occurring earlier such that a(n-1)*a(n) -1 is a prime. re-arrangement of natural numbers such that the product of adjacent terms is one more than a prime.

Table of values

List of values

n	a(n)
1	1
2	3
3	2
4	4
5	5
6	6
7	7
8	12
9	9
10	8
11	10
12	11
13	18
14	13
15	14
16	16
17	15
18	24
19	20
20	19
21	30
22	17
23	22
24	21
25	28
26	23
27	36
28	27
29	26
30	33
31	40
32	32
33	31
34	42
35	25
36	50
37	34
38	38
39	39
40	48
41	43
42	60
43	35
44	46
45	45
46	44
47	37
48	54
49	41
50	52
51	57
52	56
53	55
54	68
55	49
56	62
57	64
58	53
59	70
60	29
61	66
62	63
63	76
64	47
65	82
66	69
67	58
68	51
69	72
70	61

n	a(n)
1	1
2	3
3	2
4	4
5	5
6	6
7	7
8	12
9	9
10	8
11	10
12	11
13	18
14	13
15	14
16	16
17	15
18	24
19	20
20	19
21	30
22	17
23	22
24	21
25	28
26	23
27	36
28	27
29	26
30	33
31	40
32	32
33	31
34	42
35	25
36	50
37	34
38	38
39	39
40	48
41	43
42	60
43	35
44	46
45	45
46	44
47	37
48	54
49	41
50	52
51	57
52	56
53	55
54	68
55	49
56	62
57	64
58	53
59	70
60	29
61	66
62	63
63	76
64	47
65	82
66	69
67	58
68	51
69	72
70	61

n	a(n)
1	1
2	3
3	2
4	4
5	5
6	6
7	7
8	12
9	9
10	8
11	10
12	11
13	18
14	13
15	14
16	16
17	15
18	24
19	20
20	19
21	30
22	17
23	22
24	21
25	28
26	23
27	36
28	27
29	26
30	33
31	40
32	32
33	31
34	42
35	25
36	50
37	34
38	38
39	39
40	48
41	43
42	60
43	35
44	46
45	45
46	44
47	37
48	54
49	41
50	52
51	57
52	56
53	55
54	68
55	49
56	62
57	64
58	53
59	70
60	29
61	66
62	63
63	76
64	47
65	82
66	69
67	58
68	51
69	72
70	61