A066437 - cp's OEIS frontend

A066437 a(n) = max_{k} {T(n,k)} where T(n,k) is the "phi/sigma tug-of-war sequence with seed n" defined by T(n,1) = phi(n), T(n,2) = sigma(phi(n)), T(n,3) = phi(sigma(phi(n))), ..., T(n,k) = phi(T(n,k-1)) if k is odd and = sigma(T(n,k-1)) if k is even.

n	a(n)
1	1
2	1
3	3
4	3
5	12
6	3
7	12
8	12
9	12
10	12
11	18
12	12
13	28
14	12
15	15
16	15
17	72
18	12
19	72
20	15
21	28
22	18
23	36
24	15
25	42
26	28
27	72
28	28
29	72
30	15
31	72
32	72
33	42
34	72
35	72
36	28
37	252
38	72
39	72
40	72
41	90
42	28
43	252
44	42
45	72
46	36
47	72
48	72
49	252
50	42
51	252
52	72
53	252
54	72
55	90
56	72
57	252
58	72
59	90
60	72
61	168
62	72
63	252
64	252
65	168
66	42

[1, 1, 3, 3, 12, 3, 12, 12, 12, 12, 18, 12, 28, 12, 15, 15, 72, 12, 72, 15, 28, 18, 36, 15, 42, 28, 72, 28, 72, 15, 72, 72, 42, 72, 72, 28, 252, 72, 72, 72, 90, 28, 252, 42, 72, 36, 72, 72, 252, 42, 252, 72, 252, 72, 90, 72, 252, 72, 90, 72, 168, 72, 252, 252, 168, 42]

cp's OEIS Frontend

A066437 a(n) = max_{k} {T(n,k)} where T(n,k) is the "phi/sigma tug-of-war sequence with seed n" defined by T(n,1) = phi(n), T(n,2) = sigma(phi(n)), T(n,3) = phi(sigma(phi(n))), ..., T(n,k) = phi(T(n,k-1)) if k is odd and = sigma(T(n,k-1)) if k is even.

Table of values

List of values

n	a(n)
1	1
2	1
3	3
4	3
5	12
6	3
7	12
8	12
9	12
10	12
11	18
12	12
13	28
14	12
15	15
16	15
17	72
18	12
19	72
20	15
21	28
22	18
23	36
24	15
25	42
26	28
27	72
28	28
29	72
30	15
31	72
32	72
33	42
34	72
35	72
36	28
37	252
38	72
39	72
40	72
41	90
42	28
43	252
44	42
45	72
46	36
47	72
48	72
49	252
50	42
51	252
52	72
53	252
54	72
55	90
56	72
57	252
58	72
59	90
60	72
61	168
62	72
63	252
64	252
65	168
66	42

n	a(n)
1	1
2	1
3	3
4	3
5	12
6	3
7	12
8	12
9	12
10	12
11	18
12	12
13	28
14	12
15	15
16	15
17	72
18	12
19	72
20	15
21	28
22	18
23	36
24	15
25	42
26	28
27	72
28	28
29	72
30	15
31	72
32	72
33	42
34	72
35	72
36	28
37	252
38	72
39	72
40	72
41	90
42	28
43	252
44	42
45	72
46	36
47	72
48	72
49	252
50	42
51	252
52	72
53	252
54	72
55	90
56	72
57	252
58	72
59	90
60	72
61	168
62	72
63	252
64	252
65	168
66	42

n	a(n)
1	1
2	1
3	3
4	3
5	12
6	3
7	12
8	12
9	12
10	12
11	18
12	12
13	28
14	12
15	15
16	15
17	72
18	12
19	72
20	15
21	28
22	18
23	36
24	15
25	42
26	28
27	72
28	28
29	72
30	15
31	72
32	72
33	42
34	72
35	72
36	28
37	252
38	72
39	72
40	72
41	90
42	28
43	252
44	42
45	72
46	36
47	72
48	72
49	252
50	42
51	252
52	72
53	252
54	72
55	90
56	72
57	252
58	72
59	90
60	72
61	168
62	72
63	252
64	252
65	168
66	42