A216623 - cp's OEIS frontend

A216623 Triangle read by rows, n>=1, 1<=k<=n, T(n,k) = Sum_{c|n,d|k} phi(lcm(c,d)).

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	7
7	4
8	8
9	12
10	14
11	5
12	10
13	15
14	20
15	13
16	6
17	12
18	14
19	24
20	30
21	28
22	7
23	14
24	21
25	28
26	35
27	42
28	19
29	8
30	16
31	24
32	26
33	40
34	48
35	56
36	42
37	9
38	18
39	19
40	36
41	45
42	38
43	63
44	72
45	37
46	10
47	20
48	30
49	40
50	26
51	60
52	70
53	80
54	90
55	52
56	11
57	22
58	33
59	44
60	55
61	66
62	77
63	88
64	99
65	110
66	31
67	12
68	24

[1, 2, 4, 3, 6, 7, 4, 8, 12, 14, 5, 10, 15, 20, 13, 6, 12, 14, 24, 30, 28, 7, 14, 21, 28, 35, 42, 19, 8, 16, 24, 26, 40, 48, 56, 42, 9, 18, 19, 36, 45, 38, 63, 72, 37, 10, 20, 30, 40, 26, 60, 70, 80, 90, 52, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 31, 12, 24]

cp's OEIS Frontend

A216623 Triangle read by rows, n>=1, 1<=k<=n, T(n,k) = Sum_{c|n,d|k} phi(lcm(c,d)).

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	7
7	4
8	8
9	12
10	14
11	5
12	10
13	15
14	20
15	13
16	6
17	12
18	14
19	24
20	30
21	28
22	7
23	14
24	21
25	28
26	35
27	42
28	19
29	8
30	16
31	24
32	26
33	40
34	48
35	56
36	42
37	9
38	18
39	19
40	36
41	45
42	38
43	63
44	72
45	37
46	10
47	20
48	30
49	40
50	26
51	60
52	70
53	80
54	90
55	52
56	11
57	22
58	33
59	44
60	55
61	66
62	77
63	88
64	99
65	110
66	31
67	12
68	24

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	7
7	4
8	8
9	12
10	14
11	5
12	10
13	15
14	20
15	13
16	6
17	12
18	14
19	24
20	30
21	28
22	7
23	14
24	21
25	28
26	35
27	42
28	19
29	8
30	16
31	24
32	26
33	40
34	48
35	56
36	42
37	9
38	18
39	19
40	36
41	45
42	38
43	63
44	72
45	37
46	10
47	20
48	30
49	40
50	26
51	60
52	70
53	80
54	90
55	52
56	11
57	22
58	33
59	44
60	55
61	66
62	77
63	88
64	99
65	110
66	31
67	12
68	24

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	7
7	4
8	8
9	12
10	14
11	5
12	10
13	15
14	20
15	13
16	6
17	12
18	14
19	24
20	30
21	28
22	7
23	14
24	21
25	28
26	35
27	42
28	19
29	8
30	16
31	24
32	26
33	40
34	48
35	56
36	42
37	9
38	18
39	19
40	36
41	45
42	38
43	63
44	72
45	37
46	10
47	20
48	30
49	40
50	26
51	60
52	70
53	80
54	90
55	52
56	11
57	22
58	33
59	44
60	55
61	66
62	77
63	88
64	99
65	110
66	31
67	12
68	24