A383442 - cp's OEIS frontend

A383442 a(0) = 0; thereafter a(n) is the least integer (in absolute value) not yet in the sequence such that the absolute difference between a(n-1) and a(n) is a triangular number; in case of a tie, preference is given to the positive value.

n	a(n)
0	0
1	1
2	2
3	-1
4	-2
5	-3
6	3
7	4
8	5
9	-5
10	-4
11	6
12	7
13	8
14	-7
15	-6
16	9
17	10
18	11
19	-10
20	-9
21	-8
22	-11
23	-12
24	-13
25	-14
26	14
27	13
28	12
29	15
30	16
31	17
32	18
33	-18
34	-15
35	-16
36	-17
37	19
38	20
39	21
40	22
41	23
42	-22
43	-19
44	-20
45	-21
46	24
47	25
48	26
49	27
50	28
51	-27
52	-24
53	-23
54	-26
55	-25
56	-28
57	-29
58	-30
59	-31
60	-32
61	-33
62	33
63	30
64	29
65	32
66	31
67	34
68	35
69	36
70	37
71	38
72	39
73	-39
74	-36
75	-35
76	-34
77	-37
78	-38
79	40

[0, 1, 2, -1, -2, -3, 3, 4, 5, -5, -4, 6, 7, 8, -7, -6, 9, 10, 11, -10, -9, -8, -11, -12, -13, -14, 14, 13, 12, 15, 16, 17, 18, -18, -15, -16, -17, 19, 20, 21, 22, 23, -22, -19, -20, -21, 24, 25, 26, 27, 28, -27, -24, -23, -26, -25, -28, -29, -30, -31, -32, -33, 33, 30, 29, 32, 31, 34, 35, 36, 37, 38, 39, -39, -36, -35, -34, -37, -38, 40]

cp's OEIS Frontend

A383442 a(0) = 0; thereafter a(n) is the least integer (in absolute value) not yet in the sequence such that the absolute difference between a(n-1) and a(n) is a triangular number; in case of a tie, preference is given to the positive value.

Table of values

List of values

n	a(n)
0	0
1	1
2	2
3	-1
4	-2
5	-3
6	3
7	4
8	5
9	-5
10	-4
11	6
12	7
13	8
14	-7
15	-6
16	9
17	10
18	11
19	-10
20	-9
21	-8
22	-11
23	-12
24	-13
25	-14
26	14
27	13
28	12
29	15
30	16
31	17
32	18
33	-18
34	-15
35	-16
36	-17
37	19
38	20
39	21
40	22
41	23
42	-22
43	-19
44	-20
45	-21
46	24
47	25
48	26
49	27
50	28
51	-27
52	-24
53	-23
54	-26
55	-25
56	-28
57	-29
58	-30
59	-31
60	-32
61	-33
62	33
63	30
64	29
65	32
66	31
67	34
68	35
69	36
70	37
71	38
72	39
73	-39
74	-36
75	-35
76	-34
77	-37
78	-38
79	40

n	a(n)
0	0
1	1
2	2
3	-1
4	-2
5	-3
6	3
7	4
8	5
9	-5
10	-4
11	6
12	7
13	8
14	-7
15	-6
16	9
17	10
18	11
19	-10
20	-9
21	-8
22	-11
23	-12
24	-13
25	-14
26	14
27	13
28	12
29	15
30	16
31	17
32	18
33	-18
34	-15
35	-16
36	-17
37	19
38	20
39	21
40	22
41	23
42	-22
43	-19
44	-20
45	-21
46	24
47	25
48	26
49	27
50	28
51	-27
52	-24
53	-23
54	-26
55	-25
56	-28
57	-29
58	-30
59	-31
60	-32
61	-33
62	33
63	30
64	29
65	32
66	31
67	34
68	35
69	36
70	37
71	38
72	39
73	-39
74	-36
75	-35
76	-34
77	-37
78	-38
79	40

n	a(n)
0	0
1	1
2	2
3	-1
4	-2
5	-3
6	3
7	4
8	5
9	-5
10	-4
11	6
12	7
13	8
14	-7
15	-6
16	9
17	10
18	11
19	-10
20	-9
21	-8
22	-11
23	-12
24	-13
25	-14
26	14
27	13
28	12
29	15
30	16
31	17
32	18
33	-18
34	-15
35	-16
36	-17
37	19
38	20
39	21
40	22
41	23
42	-22
43	-19
44	-20
45	-21
46	24
47	25
48	26
49	27
50	28
51	-27
52	-24
53	-23
54	-26
55	-25
56	-28
57	-29
58	-30
59	-31
60	-32
61	-33
62	33
63	30
64	29
65	32
66	31
67	34
68	35
69	36
70	37
71	38
72	39
73	-39
74	-36
75	-35
76	-34
77	-37
78	-38
79	40