A147980 - cp's OEIS frontend

A147980 Given a set of positive integers A={1,2,...,n-1,n}, n>=2. Take subsets of A of the form {1,...,n} so only subsets containing numbers 1 and n are allowed. Then a(1)=1 and a(n) is the number of subsets where arithmetic mean of the subset is an integer.

n	a(n)
1	1
2	0
3	2
4	0
5	4
6	4
7	8
8	12
9	28
10	44
11	84
12	156
13	288
14	540
15	1020
16	1904
17	3616
18	6860
19	13024
20	24836
21	47448
22	90772
23	174072
24	334348
25	643112
26	1238928
27	2389956
28	4615916
29	8925808
30	17278680
31	33482196
32	64944060
33	126083448
34	244989096
35	476416560
36	927167752
37	1805691728
38	3519062820

[1, 0, 2, 0, 4, 4, 8, 12, 28, 44, 84, 156, 288, 540, 1020, 1904, 3616, 6860, 13024, 24836, 47448, 90772, 174072, 334348, 643112, 1238928, 2389956, 4615916, 8925808, 17278680, 33482196, 64944060, 126083448, 244989096, 476416560, 927167752, 1805691728, 3519062820]

cp's OEIS Frontend

A147980 Given a set of positive integers A={1,2,...,n-1,n}, n>=2. Take subsets of A of the form {1,...,n} so only subsets containing numbers 1 and n are allowed. Then a(1)=1 and a(n) is the number of subsets where arithmetic mean of the subset is an integer.

Table of values

List of values