A305538 - cp's OEIS frontend

A305538 a(n) is the smallest positive generalized pentagonal number such that A001318(n) - a(n) is twice a generalized pentagonal number.

n	a(n)
3	1
4	3
5	2
6	1
7	8
8	2
9	5
10	10
11	7
12	5
13	18
14	7
15	12
16	20
17	3
18	12
19	5
20	1
21	22
22	3
23	10
24	22
25	13
26	8
27	35
28	11
29	20
30	35
31	2
32	18
33	5
34	22
35	33
36	1
37	12
38	31
39	16
40	8
41	49
42	12
43	25
44	47
45	30
46	21
47	2
48	26
49	41
50	66
51	11
52	37
53	16
54	5
55	60
56	10
57	27
58	56
59	33
60	21
61	82
62	27
63	46
64	78
65	7
66	40
67	13
68	47
69	68
70	5
71	26
72	62
73	33

[1, 3, 2, 1, 8, 2, 5, 10, 7, 5, 18, 7, 12, 20, 3, 12, 5, 1, 22, 3, 10, 22, 13, 8, 35, 11, 20, 35, 2, 18, 5, 22, 33, 1, 12, 31, 16, 8, 49, 12, 25, 47, 30, 21, 2, 26, 41, 66, 11, 37, 16, 5, 60, 10, 27, 56, 33, 21, 82, 27, 46, 78, 7, 40, 13, 47, 68, 5, 26, 62, 33]

cp's OEIS Frontend

A305538 a(n) is the smallest positive generalized pentagonal number such that A001318(n) - a(n) is twice a generalized pentagonal number.

Table of values

List of values

n	a(n)
3	1
4	3
5	2
6	1
7	8
8	2
9	5
10	10
11	7
12	5
13	18
14	7
15	12
16	20
17	3
18	12
19	5
20	1
21	22
22	3
23	10
24	22
25	13
26	8
27	35
28	11
29	20
30	35
31	2
32	18
33	5
34	22
35	33
36	1
37	12
38	31
39	16
40	8
41	49
42	12
43	25
44	47
45	30
46	21
47	2
48	26
49	41
50	66
51	11
52	37
53	16
54	5
55	60
56	10
57	27
58	56
59	33
60	21
61	82
62	27
63	46
64	78
65	7
66	40
67	13
68	47
69	68
70	5
71	26
72	62
73	33

n	a(n)
3	1
4	3
5	2
6	1
7	8
8	2
9	5
10	10
11	7
12	5
13	18
14	7
15	12
16	20
17	3
18	12
19	5
20	1
21	22
22	3
23	10
24	22
25	13
26	8
27	35
28	11
29	20
30	35
31	2
32	18
33	5
34	22
35	33
36	1
37	12
38	31
39	16
40	8
41	49
42	12
43	25
44	47
45	30
46	21
47	2
48	26
49	41
50	66
51	11
52	37
53	16
54	5
55	60
56	10
57	27
58	56
59	33
60	21
61	82
62	27
63	46
64	78
65	7
66	40
67	13
68	47
69	68
70	5
71	26
72	62
73	33

n	a(n)
3	1
4	3
5	2
6	1
7	8
8	2
9	5
10	10
11	7
12	5
13	18
14	7
15	12
16	20
17	3
18	12
19	5
20	1
21	22
22	3
23	10
24	22
25	13
26	8
27	35
28	11
29	20
30	35
31	2
32	18
33	5
34	22
35	33
36	1
37	12
38	31
39	16
40	8
41	49
42	12
43	25
44	47
45	30
46	21
47	2
48	26
49	41
50	66
51	11
52	37
53	16
54	5
55	60
56	10
57	27
58	56
59	33
60	21
61	82
62	27
63	46
64	78
65	7
66	40
67	13
68	47
69	68
70	5
71	26
72	62
73	33