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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.

A098921 Let [n] = {1,2,...,n}. Let G_n be the union of all closed line segments joining any two elements of [n] X [n] along a vertical or horizontal line, or along a line with slope +-1. Then a(n) = combined total of the number of (nondegenerate) triangles and rectangles for which all edges are subsets of G_n.

Table of values

n a(n)
1 0
2 9
3 62
4 211
5 534
6 1127
7 2112
8 3629
9 5844
10 8941
11 13130
12 18639
13 25722
14 34651
15 45724
16 59257
17 75592
18 95089
19 118134
20 145131
21 176510
22 212719
23 254232
24 301541
25 355164
26 415637
27 483522
28 559399
29 643874
30 737571
31 841140
32 955249
33 1080592

List of values

[0, 9, 62, 211, 534, 1127, 2112, 3629, 5844, 8941, 13130, 18639, 25722, 34651, 45724, 59257, 75592, 95089, 118134, 145131, 176510, 212719, 254232, 301541, 355164, 415637, 483522, 559399, 643874, 737571, 841140, 955249, 1080592]

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

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