A189536 - cp's OEIS frontend

A189536 The smallest prime p such that tau(p-1) + tau(p+1) = prime(n), or 0 if no such prime exists; where tau(k) is the number of divisors of k.

n	a(n)
1	0
2	2
3	3
4	5
5	17
6	37
7	101
8	0
9	401
10	3137
11	4357
12	62501
13	21317
14	16901
15	1008017
16	15877
17	1020101
18	33857
19	69697
20	14401
21	331777
22	78401
23	32401
24	57601
25	828101
26	40195601
27	32080897
28	3326977
29	876097
30	476101
31	199374401
32	4326401
33	14440001
34	1299601
35	33918977
36	3459601
37	2647719937
38	145540097

[0, 2, 3, 5, 17, 37, 101, 0, 401, 3137, 4357, 62501, 21317, 16901, 1008017, 15877, 1020101, 33857, 69697, 14401, 331777, 78401, 32401, 57601, 828101, 40195601, 32080897, 3326977, 876097, 476101, 199374401, 4326401, 14440001, 1299601, 33918977, 3459601, 2647719937, 145540097]

cp's OEIS Frontend

A189536 The smallest prime p such that tau(p-1) + tau(p+1) = prime(n), or 0 if no such prime exists; where tau(k) is the number of divisors of k.

Table of values

List of values