A221183 - cp's OEIS frontend

A221183 a(0)=0, a(1)=1; thereafter a(n) = gpf(2*a(n-1)+a(n-2)), where gpf = "greatest prime factor" (A006530).

n	a(n)
0	0
1	1
2	2
3	5
4	3
5	11
6	5
7	7
8	19
9	5
10	29
11	7
12	43
13	31
14	7
15	5
16	17
17	13
18	43
19	11
20	13
21	37
22	29
23	19
24	67
25	17
26	101
27	73
28	19
29	37
30	31
31	11
32	53
33	13
34	79
35	19
36	13
37	5
38	23
39	17
40	19
41	11
42	41
43	31
44	103
45	79
46	29
47	137
48	101
49	113
50	109
51	331
52	257
53	13
54	283
55	193
56	223
57	71
58	73
59	31
60	5
61	41
62	29
63	11
64	17
65	5
66	3
67	11
68	5
69	7
70	19
71	5
72	29
73	7
74	43
75	31
76	7
77	5
78	17

[0, 1, 2, 5, 3, 11, 5, 7, 19, 5, 29, 7, 43, 31, 7, 5, 17, 13, 43, 11, 13, 37, 29, 19, 67, 17, 101, 73, 19, 37, 31, 11, 53, 13, 79, 19, 13, 5, 23, 17, 19, 11, 41, 31, 103, 79, 29, 137, 101, 113, 109, 331, 257, 13, 283, 193, 223, 71, 73, 31, 5, 41, 29, 11, 17, 5, 3, 11, 5, 7, 19, 5, 29, 7, 43, 31, 7, 5, 17]

cp's OEIS Frontend

A221183 a(0)=0, a(1)=1; thereafter a(n) = gpf(2*a(n-1)+a(n-2)), where gpf = "greatest prime factor" (A006530).

Table of values

List of values

n	a(n)
0	0
1	1
2	2
3	5
4	3
5	11
6	5
7	7
8	19
9	5
10	29
11	7
12	43
13	31
14	7
15	5
16	17
17	13
18	43
19	11
20	13
21	37
22	29
23	19
24	67
25	17
26	101
27	73
28	19
29	37
30	31
31	11
32	53
33	13
34	79
35	19
36	13
37	5
38	23
39	17
40	19
41	11
42	41
43	31
44	103
45	79
46	29
47	137
48	101
49	113
50	109
51	331
52	257
53	13
54	283
55	193
56	223
57	71
58	73
59	31
60	5
61	41
62	29
63	11
64	17
65	5
66	3
67	11
68	5
69	7
70	19
71	5
72	29
73	7
74	43
75	31
76	7
77	5
78	17

n	a(n)
0	0
1	1
2	2
3	5
4	3
5	11
6	5
7	7
8	19
9	5
10	29
11	7
12	43
13	31
14	7
15	5
16	17
17	13
18	43
19	11
20	13
21	37
22	29
23	19
24	67
25	17
26	101
27	73
28	19
29	37
30	31
31	11
32	53
33	13
34	79
35	19
36	13
37	5
38	23
39	17
40	19
41	11
42	41
43	31
44	103
45	79
46	29
47	137
48	101
49	113
50	109
51	331
52	257
53	13
54	283
55	193
56	223
57	71
58	73
59	31
60	5
61	41
62	29
63	11
64	17
65	5
66	3
67	11
68	5
69	7
70	19
71	5
72	29
73	7
74	43
75	31
76	7
77	5
78	17

n	a(n)
0	0
1	1
2	2
3	5
4	3
5	11
6	5
7	7
8	19
9	5
10	29
11	7
12	43
13	31
14	7
15	5
16	17
17	13
18	43
19	11
20	13
21	37
22	29
23	19
24	67
25	17
26	101
27	73
28	19
29	37
30	31
31	11
32	53
33	13
34	79
35	19
36	13
37	5
38	23
39	17
40	19
41	11
42	41
43	31
44	103
45	79
46	29
47	137
48	101
49	113
50	109
51	331
52	257
53	13
54	283
55	193
56	223
57	71
58	73
59	31
60	5
61	41
62	29
63	11
64	17
65	5
66	3
67	11
68	5
69	7
70	19
71	5
72	29
73	7
74	43
75	31
76	7
77	5
78	17