A284047 - cp's OEIS frontend

A284047 a(n) is the smallest positive integer not already in the sequence such that a(n) + a(n-1) and a(n)^2 + a(n-1)^2 are primes, with a(1) = 1.

n	a(n)
1	1
2	2
3	3
4	8
5	5
6	6
7	11
8	20
9	23
10	18
11	35
12	24
13	19
14	10
15	7
16	12
17	17
18	42
19	25
20	4
21	9
22	14
23	15
24	22
25	57
26	32
27	27
28	52
29	37
30	30
31	13
32	28
33	33
34	40
35	39
36	34
37	45
38	16
39	31
40	70
41	69
42	80
43	21
44	26
45	41
46	56
47	51
48	50
49	53
50	48
51	65
52	36
53	71
54	60
55	29
56	44
57	59
58	54
59	85
60	46
61	81
62	100
63	49
64	90
65	61
66	76
67	91
68	66
69	101
70	96
71	55
72	58
73	73
74	108
75	43
76	120
77	79
78	84
79	145
80	78
81	103

[1, 2, 3, 8, 5, 6, 11, 20, 23, 18, 35, 24, 19, 10, 7, 12, 17, 42, 25, 4, 9, 14, 15, 22, 57, 32, 27, 52, 37, 30, 13, 28, 33, 40, 39, 34, 45, 16, 31, 70, 69, 80, 21, 26, 41, 56, 51, 50, 53, 48, 65, 36, 71, 60, 29, 44, 59, 54, 85, 46, 81, 100, 49, 90, 61, 76, 91, 66, 101, 96, 55, 58, 73, 108, 43, 120, 79, 84, 145, 78, 103]

cp's OEIS Frontend

A284047 a(n) is the smallest positive integer not already in the sequence such that a(n) + a(n-1) and a(n)^2 + a(n-1)^2 are primes, with a(1) = 1.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	8
5	5
6	6
7	11
8	20
9	23
10	18
11	35
12	24
13	19
14	10
15	7
16	12
17	17
18	42
19	25
20	4
21	9
22	14
23	15
24	22
25	57
26	32
27	27
28	52
29	37
30	30
31	13
32	28
33	33
34	40
35	39
36	34
37	45
38	16
39	31
40	70
41	69
42	80
43	21
44	26
45	41
46	56
47	51
48	50
49	53
50	48
51	65
52	36
53	71
54	60
55	29
56	44
57	59
58	54
59	85
60	46
61	81
62	100
63	49
64	90
65	61
66	76
67	91
68	66
69	101
70	96
71	55
72	58
73	73
74	108
75	43
76	120
77	79
78	84
79	145
80	78
81	103

n	a(n)
1	1
2	2
3	3
4	8
5	5
6	6
7	11
8	20
9	23
10	18
11	35
12	24
13	19
14	10
15	7
16	12
17	17
18	42
19	25
20	4
21	9
22	14
23	15
24	22
25	57
26	32
27	27
28	52
29	37
30	30
31	13
32	28
33	33
34	40
35	39
36	34
37	45
38	16
39	31
40	70
41	69
42	80
43	21
44	26
45	41
46	56
47	51
48	50
49	53
50	48
51	65
52	36
53	71
54	60
55	29
56	44
57	59
58	54
59	85
60	46
61	81
62	100
63	49
64	90
65	61
66	76
67	91
68	66
69	101
70	96
71	55
72	58
73	73
74	108
75	43
76	120
77	79
78	84
79	145
80	78
81	103

n	a(n)
1	1
2	2
3	3
4	8
5	5
6	6
7	11
8	20
9	23
10	18
11	35
12	24
13	19
14	10
15	7
16	12
17	17
18	42
19	25
20	4
21	9
22	14
23	15
24	22
25	57
26	32
27	27
28	52
29	37
30	30
31	13
32	28
33	33
34	40
35	39
36	34
37	45
38	16
39	31
40	70
41	69
42	80
43	21
44	26
45	41
46	56
47	51
48	50
49	53
50	48
51	65
52	36
53	71
54	60
55	29
56	44
57	59
58	54
59	85
60	46
61	81
62	100
63	49
64	90
65	61
66	76
67	91
68	66
69	101
70	96
71	55
72	58
73	73
74	108
75	43
76	120
77	79
78	84
79	145
80	78
81	103