A089695 - cp's OEIS frontend

A089695 Numbers m such that placing as many possible '+' signs anywhere in between the digits yields a prime in every case. Let abcd... be the digits of m; then abcd, a + bcd, ab + cd, abc + d, a + b + cd, a + bc + d, ab + c + d, a + b + c + d, ... are all prime.

n	a(n)
1	2
2	3
3	5
4	7
5	11
6	23
7	29
8	41
9	43
10	47
11	61
12	67
13	83
14	89
15	101
16	227
17	229
18	281
19	401
20	443
21	449
22	467
23	601
24	607
25	647
26	661
27	683
28	809
29	821
30	863
31	881
32	4001
33	4463
34	4643
35	6007
36	6067
37	6803
38	8009

[2, 3, 5, 7, 11, 23, 29, 41, 43, 47, 61, 67, 83, 89, 101, 227, 229, 281, 401, 443, 449, 467, 601, 607, 647, 661, 683, 809, 821, 863, 881, 4001, 4463, 4643, 6007, 6067, 6803, 8009]

cp's OEIS Frontend

A089695 Numbers m such that placing as many possible '+' signs anywhere in between the digits yields a prime in every case. Let abcd... be the digits of m; then abcd, a + bcd, ab + cd, abc + d, a + b + cd, a + bc + d, ab + c + d, a + b + c + d, ... are all prime.

Table of values

List of values