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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.

A320851 Number of 5-element subsets of [n] whose sum is a triangular number.

Table of values

n a(n)
5 1
6 1
7 4
8 9
9 18
10 35
11 61
12 100
13 156
14 235
15 342
16 482
17 664
18 895
19 1185
20 1542
21 1977
22 2505
23 3134
24 3879
25 4757
26 5782
27 6968
28 8337
29 9909
30 11699
31 13732
32 16030
33 18615
34 21514
35 24755
36 28361
37 32362
38 36789
39 41673
40 47051
41 52953
42 59412
43 66466
44 74158
45 82525
46 91611
47 101454
48 112097

List of values

[1, 1, 4, 9, 18, 35, 61, 100, 156, 235, 342, 482, 664, 895, 1185, 1542, 1977, 2505, 3134, 3879, 4757, 5782, 6968, 8337, 9909, 11699, 13732, 16030, 18615, 21514, 24755, 28361, 32362, 36789, 41673, 47051, 52953, 59412, 66466, 74158, 82525, 91611, 101454, 112097]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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