A145856 - cp's OEIS frontend

A145856 Least number k>1 such that centered n-gonal number n*k(k-1)/2+1 is a perfect square, or 0 if no such k exists.

n	a(n)
1	3
2	0
3	2
4	4
5	3
6	8
7	16
8	2
9	17
10	9
11	15
12	5
13	6
14	16
15	2
16	3
17	6
18	0
19	7
20	4
21	3
22	40
23	7
24	2
25	22
26	8
27	111
28	4
29	16
30	8
31	16
32	0
33	3
34	9
35	2
36	5
37	990
38	9
39	15
40	3
41	46
42	16
43	10
44	5
45	6
46	336
47	10
48	2
49	30
50	0
51	31
52	16
53	11
54	416
55	7
56	3
57	11
58	33
59	55
60	4
61	78
62	56
63	2
64	6
65	3
66	8
67	47751
68	12
69	16
70	24
71	48
72	0
73	49
74	25
75	17
76	13
77	6
78	9
79	2640
80	2
81	6721

[3, 0, 2, 4, 3, 8, 16, 2, 17, 9, 15, 5, 6, 16, 2, 3, 6, 0, 7, 4, 3, 40, 7, 2, 22, 8, 111, 4, 16, 8, 16, 0, 3, 9, 2, 5, 990, 9, 15, 3, 46, 16, 10, 5, 6, 336, 10, 2, 30, 0, 31, 16, 11, 416, 7, 3, 11, 33, 55, 4, 78, 56, 2, 6, 3, 8, 47751, 12, 16, 24, 48, 0, 49, 25, 17, 13, 6, 9, 2640, 2, 6721]

cp's OEIS Frontend

A145856 Least number k>1 such that centered n-gonal number n*k(k-1)/2+1 is a perfect square, or 0 if no such k exists.

Table of values

List of values