A241922 - cp's OEIS frontend

A241922 Smallest k^2>=0 such that n-k^2 is semiprime, or a(n)=2 if there is no such k^2.

n	a(n)
1	2
2	2
3	2
4	0
5	1
6	0
7	1
8	4
9	0
10	0
11	1
12	2
13	4
14	0
15	0
16	1
17	2
18	4
19	4
20	16
21	0
22	0
23	1
24	9
25	0
26	0
27	1
28	2
29	4
30	4
31	9
32	2
33	0
34	0
35	0
36	1
37	4
38	0
39	0
40	1
41	16
42	4
43	4
44	9
45	36
46	0
47	1
48	9
49	0
50	1
51	0
52	1
53	4
54	16
55	0
56	1
57	0
58	0
59	1
60	9
61	4
62	0
63	1
64	9
65	0
66	1
67	9
68	64
69	0
70	1
71	9
72	2
73	4
74	0
75	1
76	25
77	0
78	1
79	64
80	25
81	4
82	0
83	1
84	49
85	0
86	0
87	0
88	1
89	4
90	4
91	0
92	1
93	0
94	0
95	0
96	1
97	4
98	4
99	4
100	9
101	16

[2, 2, 2, 0, 1, 0, 1, 4, 0, 0, 1, 2, 4, 0, 0, 1, 2, 4, 4, 16, 0, 0, 1, 9, 0, 0, 1, 2, 4, 4, 9, 2, 0, 0, 0, 1, 4, 0, 0, 1, 16, 4, 4, 9, 36, 0, 1, 9, 0, 1, 0, 1, 4, 16, 0, 1, 0, 0, 1, 9, 4, 0, 1, 9, 0, 1, 9, 64, 0, 1, 9, 2, 4, 0, 1, 25, 0, 1, 64, 25, 4, 0, 1, 49, 0, 0, 0, 1, 4, 4, 0, 1, 0, 0, 0, 1, 4, 4, 4, 9, 16]

cp's OEIS Frontend

A241922 Smallest k^2>=0 such that n-k^2 is semiprime, or a(n)=2 if there is no such k^2.

Table of values

List of values

n	a(n)
1	2
2	2
3	2
4	0
5	1
6	0
7	1
8	4
9	0
10	0
11	1
12	2
13	4
14	0
15	0
16	1
17	2
18	4
19	4
20	16
21	0
22	0
23	1
24	9
25	0
26	0
27	1
28	2
29	4
30	4
31	9
32	2
33	0
34	0
35	0
36	1
37	4
38	0
39	0
40	1
41	16
42	4
43	4
44	9
45	36
46	0
47	1
48	9
49	0
50	1
51	0
52	1
53	4
54	16
55	0
56	1
57	0
58	0
59	1
60	9
61	4
62	0
63	1
64	9
65	0
66	1
67	9
68	64
69	0
70	1
71	9
72	2
73	4
74	0
75	1
76	25
77	0
78	1
79	64
80	25
81	4
82	0
83	1
84	49
85	0
86	0
87	0
88	1
89	4
90	4
91	0
92	1
93	0
94	0
95	0
96	1
97	4
98	4
99	4
100	9
101	16

n	a(n)
1	2
2	2
3	2
4	0
5	1
6	0
7	1
8	4
9	0
10	0
11	1
12	2
13	4
14	0
15	0
16	1
17	2
18	4
19	4
20	16
21	0
22	0
23	1
24	9
25	0
26	0
27	1
28	2
29	4
30	4
31	9
32	2
33	0
34	0
35	0
36	1
37	4
38	0
39	0
40	1
41	16
42	4
43	4
44	9
45	36
46	0
47	1
48	9
49	0
50	1
51	0
52	1
53	4
54	16
55	0
56	1
57	0
58	0
59	1
60	9
61	4
62	0
63	1
64	9
65	0
66	1
67	9
68	64
69	0
70	1
71	9
72	2
73	4
74	0
75	1
76	25
77	0
78	1
79	64
80	25
81	4
82	0
83	1
84	49
85	0
86	0
87	0
88	1
89	4
90	4
91	0
92	1
93	0
94	0
95	0
96	1
97	4
98	4
99	4
100	9
101	16

n	a(n)
1	2
2	2
3	2
4	0
5	1
6	0
7	1
8	4
9	0
10	0
11	1
12	2
13	4
14	0
15	0
16	1
17	2
18	4
19	4
20	16
21	0
22	0
23	1
24	9
25	0
26	0
27	1
28	2
29	4
30	4
31	9
32	2
33	0
34	0
35	0
36	1
37	4
38	0
39	0
40	1
41	16
42	4
43	4
44	9
45	36
46	0
47	1
48	9
49	0
50	1
51	0
52	1
53	4
54	16
55	0
56	1
57	0
58	0
59	1
60	9
61	4
62	0
63	1
64	9
65	0
66	1
67	9
68	64
69	0
70	1
71	9
72	2
73	4
74	0
75	1
76	25
77	0
78	1
79	64
80	25
81	4
82	0
83	1
84	49
85	0
86	0
87	0
88	1
89	4
90	4
91	0
92	1
93	0
94	0
95	0
96	1
97	4
98	4
99	4
100	9
101	16