A109896 - cp's OEIS frontend

A109896 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the number of terms in the 2n-th group.

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

[4, 5, 7, 7, 7, 8, 10, 13, 9, 9, 13, 7, 7, 11, 7, 13, 13, 11, 11, 15, 11, 13, 15, 13, 15, 16, 14, 11, 11, 13, 9, 17, 17, 19, 15, 15, 13, 17, 14, 8, 15, 18, 20, 15, 17, 17, 17, 9, 19, 11, 20, 20, 13, 19, 19, 15, 15, 9, 14, 14, 17, 16, 15, 18, 13, 20, 14, 14, 14, 17, 15, 15, 15, 21, 13]

cp's OEIS Frontend

A109896 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the number of terms in the 2n-th group.

Table of values

List of values

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

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

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