cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A047166 Number of nonempty subsets of {1,2,...,n} in which exactly 2/5 of the elements are <= n/2.

Table of values

n a(n)
1 0
2 0
3 0
4 0
5 1
6 3
7 12
8 24
9 60
10 100
11 205
12 315
13 630
14 980
15 2156
16 3528
17 8260
18 13692
19 31620
20 51600
21 115995
22 186945
23 418825
24 675675
25 1535391
26 2492919
27 5728086
28 9324406
29 21448791
30 34860553
31 80006668
32 129804808
33 298009048
34 483483128
35 1113181012
36 1807560972
37 4172914197

List of values

[0, 0, 0, 0, 1, 3, 12, 24, 60, 100, 205, 315, 630, 980, 2156, 3528, 8260, 13692, 31620, 51600, 115995, 186945, 418825, 675675, 1535391, 2492919, 5728086, 9324406, 21448791, 34860553, 80006668, 129804808, 298009048, 483483128, 1113181012, 1807560972, 4172914197]