A379018 - cp's OEIS frontend

A379018 a(n) is the least prime p such that p^2 < n and n - p^2 is not squarefree, or -1 if there is no such p.

n	a(n)
1	-1
2	-1
3	-1
4	-1
5	-1
6	-1
7	-1
8	2
9	-1
10	-1
11	-1
12	2
13	2
14	-1
15	-1
16	2
17	3
18	3
19	-1
20	2
21	3
22	2
23	-1
24	2
25	3
26	-1
27	3
28	2
29	2
30	-1
31	2
32	2
33	3
34	3
35	-1
36	2
37	3
38	-1
39	-1
40	2
41	3
42	-1
43	5
44	2
45	3
46	-1
47	-1
48	2
49	2
50	5
51	-1
52	2
53	2
54	2
55	-1
56	2
57	3
58	2
59	3
60	2
61	3
62	-1
63	3
64	2
65	3
66	-1
67	2
68	2
69	3
70	5
71	-1
72	2
73	3
74	5
75	5
76	2
77	3
78	-1
79	2
80	2
81	3
82	-1
83	-1
84	2
85	2
86	-1
87	-1
88	2
89	3

[-1, -1, -1, -1, -1, -1, -1, 2, -1, -1, -1, 2, 2, -1, -1, 2, 3, 3, -1, 2, 3, 2, -1, 2, 3, -1, 3, 2, 2, -1, 2, 2, 3, 3, -1, 2, 3, -1, -1, 2, 3, -1, 5, 2, 3, -1, -1, 2, 2, 5, -1, 2, 2, 2, -1, 2, 3, 2, 3, 2, 3, -1, 3, 2, 3, -1, 2, 2, 3, 5, -1, 2, 3, 5, 5, 2, 3, -1, 2, 2, 3, -1, -1, 2, 2, -1, -1, 2, 3]

cp's OEIS Frontend

A379018 a(n) is the least prime p such that p^2 < n and n - p^2 is not squarefree, or -1 if there is no such p.

Table of values

List of values

n	a(n)
1	-1
2	-1
3	-1
4	-1
5	-1
6	-1
7	-1
8	2
9	-1
10	-1
11	-1
12	2
13	2
14	-1
15	-1
16	2
17	3
18	3
19	-1
20	2
21	3
22	2
23	-1
24	2
25	3
26	-1
27	3
28	2
29	2
30	-1
31	2
32	2
33	3
34	3
35	-1
36	2
37	3
38	-1
39	-1
40	2
41	3
42	-1
43	5
44	2
45	3
46	-1
47	-1
48	2
49	2
50	5
51	-1
52	2
53	2
54	2
55	-1
56	2
57	3
58	2
59	3
60	2
61	3
62	-1
63	3
64	2
65	3
66	-1
67	2
68	2
69	3
70	5
71	-1
72	2
73	3
74	5
75	5
76	2
77	3
78	-1
79	2
80	2
81	3
82	-1
83	-1
84	2
85	2
86	-1
87	-1
88	2
89	3

n	a(n)
1	-1
2	-1
3	-1
4	-1
5	-1
6	-1
7	-1
8	2
9	-1
10	-1
11	-1
12	2
13	2
14	-1
15	-1
16	2
17	3
18	3
19	-1
20	2
21	3
22	2
23	-1
24	2
25	3
26	-1
27	3
28	2
29	2
30	-1
31	2
32	2
33	3
34	3
35	-1
36	2
37	3
38	-1
39	-1
40	2
41	3
42	-1
43	5
44	2
45	3
46	-1
47	-1
48	2
49	2
50	5
51	-1
52	2
53	2
54	2
55	-1
56	2
57	3
58	2
59	3
60	2
61	3
62	-1
63	3
64	2
65	3
66	-1
67	2
68	2
69	3
70	5
71	-1
72	2
73	3
74	5
75	5
76	2
77	3
78	-1
79	2
80	2
81	3
82	-1
83	-1
84	2
85	2
86	-1
87	-1
88	2
89	3

n	a(n)
1	-1
2	-1
3	-1
4	-1
5	-1
6	-1
7	-1
8	2
9	-1
10	-1
11	-1
12	2
13	2
14	-1
15	-1
16	2
17	3
18	3
19	-1
20	2
21	3
22	2
23	-1
24	2
25	3
26	-1
27	3
28	2
29	2
30	-1
31	2
32	2
33	3
34	3
35	-1
36	2
37	3
38	-1
39	-1
40	2
41	3
42	-1
43	5
44	2
45	3
46	-1
47	-1
48	2
49	2
50	5
51	-1
52	2
53	2
54	2
55	-1
56	2
57	3
58	2
59	3
60	2
61	3
62	-1
63	3
64	2
65	3
66	-1
67	2
68	2
69	3
70	5
71	-1
72	2
73	3
74	5
75	5
76	2
77	3
78	-1
79	2
80	2
81	3
82	-1
83	-1
84	2
85	2
86	-1
87	-1
88	2
89	3