A225844 - cp's OEIS frontend

A225844 Least k>0 such that triangular(n) + k*(k+1) is a triangular number.

n	a(n)
0	2
1	1
2	3
3	5
4	7
5	2
6	11
7	13
8	5
9	17
10	19
11	3
12	6
13	25
14	27
15	9
16	31
17	33
18	35
19	4
20	9
21	41
22	8
23	45
24	47
25	10
26	14
27	53
28	9
29	5
30	59
31	61
32	21
33	18
34	67
35	69
36	21
37	73
38	75
39	14
40	22
41	6
42	11
43	13
44	87
45	15
46	91
47	26
48	20
49	34
50	12
51	101
52	26
53	105
54	30
55	7
56	20
57	33
58	115
59	117
60	119
61	34
62	21
63	125
64	37
65	129
66	29
67	133
68	14
69	137

[2, 1, 3, 5, 7, 2, 11, 13, 5, 17, 19, 3, 6, 25, 27, 9, 31, 33, 35, 4, 9, 41, 8, 45, 47, 10, 14, 53, 9, 5, 59, 61, 21, 18, 67, 69, 21, 73, 75, 14, 22, 6, 11, 13, 87, 15, 91, 26, 20, 34, 12, 101, 26, 105, 30, 7, 20, 33, 115, 117, 119, 34, 21, 125, 37, 129, 29, 133, 14, 137]

cp's OEIS Frontend

A225844 Least k>0 such that triangular(n) + k*(k+1) is a triangular number.

Table of values

List of values

n	a(n)
0	2
1	1
2	3
3	5
4	7
5	2
6	11
7	13
8	5
9	17
10	19
11	3
12	6
13	25
14	27
15	9
16	31
17	33
18	35
19	4
20	9
21	41
22	8
23	45
24	47
25	10
26	14
27	53
28	9
29	5
30	59
31	61
32	21
33	18
34	67
35	69
36	21
37	73
38	75
39	14
40	22
41	6
42	11
43	13
44	87
45	15
46	91
47	26
48	20
49	34
50	12
51	101
52	26
53	105
54	30
55	7
56	20
57	33
58	115
59	117
60	119
61	34
62	21
63	125
64	37
65	129
66	29
67	133
68	14
69	137

n	a(n)
0	2
1	1
2	3
3	5
4	7
5	2
6	11
7	13
8	5
9	17
10	19
11	3
12	6
13	25
14	27
15	9
16	31
17	33
18	35
19	4
20	9
21	41
22	8
23	45
24	47
25	10
26	14
27	53
28	9
29	5
30	59
31	61
32	21
33	18
34	67
35	69
36	21
37	73
38	75
39	14
40	22
41	6
42	11
43	13
44	87
45	15
46	91
47	26
48	20
49	34
50	12
51	101
52	26
53	105
54	30
55	7
56	20
57	33
58	115
59	117
60	119
61	34
62	21
63	125
64	37
65	129
66	29
67	133
68	14
69	137

n	a(n)
0	2
1	1
2	3
3	5
4	7
5	2
6	11
7	13
8	5
9	17
10	19
11	3
12	6
13	25
14	27
15	9
16	31
17	33
18	35
19	4
20	9
21	41
22	8
23	45
24	47
25	10
26	14
27	53
28	9
29	5
30	59
31	61
32	21
33	18
34	67
35	69
36	21
37	73
38	75
39	14
40	22
41	6
42	11
43	13
44	87
45	15
46	91
47	26
48	20
49	34
50	12
51	101
52	26
53	105
54	30
55	7
56	20
57	33
58	115
59	117
60	119
61	34
62	21
63	125
64	37
65	129
66	29
67	133
68	14
69	137