A124780 - cp's OEIS frontend

A124780 a(n) = gcd(A(n), A(n+2)) where A(n) = A000522(n) = Sum_{k=0..n} n!/k!.

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

[1, 2, 5, 2, 1, 2, 1, 10, 1, 2, 13, 2, 5, 2, 1, 2, 1, 10, 1, 2, 1, 2, 5, 26, 1, 2, 1, 10, 1, 2, 1, 2, 5, 2, 37, 2, 13, 10, 1, 2, 1, 2, 5, 2, 1, 2, 1, 10, 1, 26, 1, 2, 5, 2, 1, 2, 1, 10, 1, 2, 1, 2, 65, 2, 1, 2, 1, 10, 1, 2, 1, 74, 5, 2, 1, 26, 1, 10, 1, 2, 1, 2, 5, 2, 1, 2, 1, 10, 13, 2, 1, 2, 5, 2, 1, 2, 1]

cp's OEIS Frontend

A124780 a(n) = gcd(A(n), A(n+2)) where A(n) = A000522(n) = Sum_{k=0..n} n!/k!.

Table of values

List of values

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

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

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