A278573 - cp's OEIS frontend

A278573 Irregular triangle read by rows: row n lists values of k in range 1 <= k <= n-1 such x^n + x^k + 1 is irreducible (mod 2), or -1 if no such k exists.

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

[1, 1, 2, 1, 3, 2, 3, 1, 3, 5, 1, 3, 4, 6, -1, 1, 4, 5, 8, 3, 7, 2, 9, 3, 5, 7, 9, -1, 5, 9, 1, 4, 7, 8, 11, 14, -1, 3, 5, 6, 11, 12, 14, 3, 7, 9, 11, 15, -1, 3, 5, 15, 17, 2, 7, 14, 19, 1, 21, 5, 9, 14, 18, -1, 3, 7, 18, 22, -1, -1, 1, 3, 9, 13, 15, 19, 25, 27, 2, 27, 1, 9, 21, 29, 3, 6, 7, 13]

cp's OEIS Frontend

A278573 Irregular triangle read by rows: row n lists values of k in range 1 <= k <= n-1 such x^n + x^k + 1 is irreducible (mod 2), or -1 if no such k exists.

Table of values

List of values

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

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

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