A075023 - cp's OEIS frontend

A075023 a(n) = the smallest prime divisor of A173426(n) = concatenation of (1, 2, 3,..., n, n-1, ..., 1) for n > 1; a(1) = 1.

n	a(n)
1	1
2	11
3	3
4	11
5	41
6	3
7	239
8	11
9	3
10	12345678910987654321
11	7
12	3
13	1109
14	7
15	3
16	71
17	7
18	3
19	251
20	7
21	3
22	70607
23	7
24	3
25	989931671244066864878631629
26	7
27	3
28	149
29	7
30	3
31	827
32	7
33	3
34	197
35	7
36	3
37	39907897297
38	7
39	3
40	17047
41	7
42	3
43	191
44	7
45	3
46	967
47	7
48	3
49	139121
50	7
51	3
52	109
53	7
54	3
55	5333
56	7
57	3

[1, 11, 3, 11, 41, 3, 239, 11, 3, 12345678910987654321, 7, 3, 1109, 7, 3, 71, 7, 3, 251, 7, 3, 70607, 7, 3, 989931671244066864878631629, 7, 3, 149, 7, 3, 827, 7, 3, 197, 7, 3, 39907897297, 7, 3, 17047, 7, 3, 191, 7, 3, 967, 7, 3, 139121, 7, 3, 109, 7, 3, 5333, 7, 3]

cp's OEIS Frontend

A075023 a(n) = the smallest prime divisor of A173426(n) = concatenation of (1, 2, 3,..., n, n-1, ..., 1) for n > 1; a(1) = 1.

Table of values

List of values