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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.

A131113 T(n,k) = 5*binomial(n,k) - 4*I(n,k), where I is the identity matrix; triangle T read by rows (n >= 0 and 0 <= k <= n).

Table of values

n a(n)
0 1
1 5
2 1
3 5
4 10
5 1
6 5
7 15
8 15
9 1
10 5
11 20
12 30
13 20
14 1
15 5
16 25
17 50
18 50
19 25
20 1
21 5
22 30
23 75
24 100
25 75
26 30
27 1
28 5
29 35
30 105
31 175
32 175
33 105
34 35
35 1
36 5
37 40
38 140
39 280
40 350
41 280
42 140
43 40
44 1
45 5
46 45
47 180
48 420
49 630
50 630
51 420
52 180
53 45
54 1

List of values

[1, 5, 1, 5, 10, 1, 5, 15, 15, 1, 5, 20, 30, 20, 1, 5, 25, 50, 50, 25, 1, 5, 30, 75, 100, 75, 30, 1, 5, 35, 105, 175, 175, 105, 35, 1, 5, 40, 140, 280, 350, 280, 140, 40, 1, 5, 45, 180, 420, 630, 630, 420, 180, 45, 1]

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

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