A212615 - cp's OEIS frontend

A212615 Least k > 1 such that the product pen(n) * pen(k) is pentagonal, or zero if no such k exists, where pen(k) is the k-th pentagonal number.

n	a(n)
1	2
2	39
3	2231
4	40
5	14
6	94974
7	47
8	212
9	1071
10	477
11	124
12	261
13	15120
14	5
15	180
16	375638
17	2413
18	22
19	4270831
20	924
21	278
22	18
23	126
24	33510
25	355
26	376
27	9047610
28	37313170
29	1533015
30	7315
31	1687018
32	520
33	363155
34	8827
35	13514
36	11701449166
37	670
38	3290
39	2
40	4
41	817
42	31175067

[2, 39, 2231, 40, 14, 94974, 47, 212, 1071, 477, 124, 261, 15120, 5, 180, 375638, 2413, 22, 4270831, 924, 278, 18, 126, 33510, 355, 376, 9047610, 37313170, 1533015, 7315, 1687018, 520, 363155, 8827, 13514, 11701449166, 670, 3290, 2, 4, 817, 31175067]

cp's OEIS Frontend

A212615 Least k > 1 such that the product pen(n) * pen(k) is pentagonal, or zero if no such k exists, where pen(k) is the k-th pentagonal number.

Table of values

List of values