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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.

A322240 a(n) = A084605(n)^2, the square of the central coefficient in (1 + x + 4*x^2)^n.

Table of values

n a(n)
0 1
1 1
2 81
3 625
4 21025
5 314721
6 8071281
7 155975121
8 3685097025
9 79065004225
10 1832690505361
11 41201108978481
12 955863424195681
13 22002282841672225
14 513656632397480625
15 11987246142597870225
16 281793325930991748225
17 6636532731958908324225
18 156986802654088221500625
19 3721955785026092495600625
20 88512056987508595608293025

List of values

[1, 1, 81, 625, 21025, 314721, 8071281, 155975121, 3685097025, 79065004225, 1832690505361, 41201108978481, 955863424195681, 22002282841672225, 513656632397480625, 11987246142597870225, 281793325930991748225, 6636532731958908324225, 156986802654088221500625, 3721955785026092495600625, 88512056987508595608293025]

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

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