A331044 - cp's OEIS frontend

A331044 a(n) is the greatest prime number of the form floor(n/10^k) for some k >= 0, or 0 if no such prime number exists.

n	a(n)
0	0
1	0
2	2
3	3
4	0
5	5
6	0
7	7
8	0
9	0
10	0
11	11
12	0
13	13
14	0
15	0
16	0
17	17
18	0
19	19
20	2
21	2
22	2
23	23
24	2
25	2
26	2
27	2
28	2
29	29
30	3
31	31
32	3
33	3
34	3
35	3
36	3
37	37
38	3
39	3
40	0
41	41
42	0
43	43
44	0
45	0
46	0
47	47
48	0
49	0
50	5
51	5
52	5
53	53
54	5
55	5
56	5
57	5
58	5
59	59
60	0
61	61
62	0
63	0
64	0
65	0
66	0
67	67
68	0
69	0
70	7
71	71
72	7
73	73
74	7
75	7
76	7
77	7
78	7
79	79
80	0

[0, 0, 2, 3, 0, 5, 0, 7, 0, 0, 0, 11, 0, 13, 0, 0, 0, 17, 0, 19, 2, 2, 2, 23, 2, 2, 2, 2, 2, 29, 3, 31, 3, 3, 3, 3, 3, 37, 3, 3, 0, 41, 0, 43, 0, 0, 0, 47, 0, 0, 5, 5, 5, 53, 5, 5, 5, 5, 5, 59, 0, 61, 0, 0, 0, 0, 0, 67, 0, 0, 7, 71, 7, 73, 7, 7, 7, 7, 7, 79, 0]

cp's OEIS Frontend

A331044 a(n) is the greatest prime number of the form floor(n/10^k) for some k >= 0, or 0 if no such prime number exists.

Table of values

List of values

n	a(n)
0	0
1	0
2	2
3	3
4	0
5	5
6	0
7	7
8	0
9	0
10	0
11	11
12	0
13	13
14	0
15	0
16	0
17	17
18	0
19	19
20	2
21	2
22	2
23	23
24	2
25	2
26	2
27	2
28	2
29	29
30	3
31	31
32	3
33	3
34	3
35	3
36	3
37	37
38	3
39	3
40	0
41	41
42	0
43	43
44	0
45	0
46	0
47	47
48	0
49	0
50	5
51	5
52	5
53	53
54	5
55	5
56	5
57	5
58	5
59	59
60	0
61	61
62	0
63	0
64	0
65	0
66	0
67	67
68	0
69	0
70	7
71	71
72	7
73	73
74	7
75	7
76	7
77	7
78	7
79	79
80	0

n	a(n)
0	0
1	0
2	2
3	3
4	0
5	5
6	0
7	7
8	0
9	0
10	0
11	11
12	0
13	13
14	0
15	0
16	0
17	17
18	0
19	19
20	2
21	2
22	2
23	23
24	2
25	2
26	2
27	2
28	2
29	29
30	3
31	31
32	3
33	3
34	3
35	3
36	3
37	37
38	3
39	3
40	0
41	41
42	0
43	43
44	0
45	0
46	0
47	47
48	0
49	0
50	5
51	5
52	5
53	53
54	5
55	5
56	5
57	5
58	5
59	59
60	0
61	61
62	0
63	0
64	0
65	0
66	0
67	67
68	0
69	0
70	7
71	71
72	7
73	73
74	7
75	7
76	7
77	7
78	7
79	79
80	0

n	a(n)
0	0
1	0
2	2
3	3
4	0
5	5
6	0
7	7
8	0
9	0
10	0
11	11
12	0
13	13
14	0
15	0
16	0
17	17
18	0
19	19
20	2
21	2
22	2
23	23
24	2
25	2
26	2
27	2
28	2
29	29
30	3
31	31
32	3
33	3
34	3
35	3
36	3
37	37
38	3
39	3
40	0
41	41
42	0
43	43
44	0
45	0
46	0
47	47
48	0
49	0
50	5
51	5
52	5
53	53
54	5
55	5
56	5
57	5
58	5
59	59
60	0
61	61
62	0
63	0
64	0
65	0
66	0
67	67
68	0
69	0
70	7
71	71
72	7
73	73
74	7
75	7
76	7
77	7
78	7
79	79
80	0