A083677 - cp's OEIS frontend

A083677 Define f(n, k) to be the concatenation of the first n primes, with n-1 k's inserted between the primes. Then a(n) is the smallest k >= 0 such that f(n, k) is prime, or -1 if no such prime exists.

n	a(n)
1	0
2	2
3	-1
4	1
5	4
6	10
7	38
8	20
9	0
10	-1
11	163
12	46
13	8
14	53
15	0
16	-1
17	74
18	5
19	8
20	5
21	180
22	4
23	280
24	191
25	0
26	337
27	191
28	-1
29	105
30	88
31	19
32	28
33	111
34	-1
35	525
36	13
37	24
38	102
39	159
40	-1
41	288
42	142
43	31
44	743
45	81
46	-1
47	183
48	202
49	100
50	96
51	380
52	-1
53	1227
54	5
55	113
56	123
57	20
58	23
59	0
60	48
61	148
62	438
63	52
64	144
65	128
66	297
67	206

[0, 2, -1, 1, 4, 10, 38, 20, 0, -1, 163, 46, 8, 53, 0, -1, 74, 5, 8, 5, 180, 4, 280, 191, 0, 337, 191, -1, 105, 88, 19, 28, 111, -1, 525, 13, 24, 102, 159, -1, 288, 142, 31, 743, 81, -1, 183, 202, 100, 96, 380, -1, 1227, 5, 113, 123, 20, 23, 0, 48, 148, 438, 52, 144, 128, 297, 206]

cp's OEIS Frontend

A083677 Define f(n, k) to be the concatenation of the first n primes, with n-1 k's inserted between the primes. Then a(n) is the smallest k >= 0 such that f(n, k) is prime, or -1 if no such prime exists.

Table of values

List of values