A239969 - cp's OEIS frontend

A239969 Least positive k such that triangular(n) + triangular(n+k) is a triangular number (A000217), or -1 if no such k exists.

n	a(n)
3	2
4	5
5	1
6	3
7	20
8	2
9	4
10	16
11	3
12	5
13	31
14	4
15	6
16	119
17	5
18	7
19	16
20	6
21	8
22	103
23	7
24	9
25	2
26	8
27	10
28	26
29	9
30	11
31	464
32	10
33	12
34	1
35	11
36	13
37	313
38	12
39	5
40	58
41	13
42	15
43	37
44	14
45	3
46	493
47	15
48	17
49	31
50	16
51	18
52	47
53	17
54	2
55	79
56	9
57	20
58	796
59	19
60	21
61	883
62	20
63	22
64	89
65	4
66	23
67	58
68	22
69	24
70	100
71	23
72	25
73	1276

[2, 5, 1, 3, 20, 2, 4, 16, 3, 5, 31, 4, 6, 119, 5, 7, 16, 6, 8, 103, 7, 9, 2, 8, 10, 26, 9, 11, 464, 10, 12, 1, 11, 13, 313, 12, 5, 58, 13, 15, 37, 14, 3, 493, 15, 17, 31, 16, 18, 47, 17, 2, 79, 9, 20, 796, 19, 21, 883, 20, 22, 89, 4, 23, 58, 22, 24, 100, 23, 25, 1276]

cp's OEIS Frontend

A239969 Least positive k such that triangular(n) + triangular(n+k) is a triangular number (A000217), or -1 if no such k exists.

Table of values

List of values