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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.

A201807 Number of arrays of n integers in -4..4 with sum zero and equal numbers of elements greater than zero and less than zero.

Table of values

n a(n)
1 1
2 9
3 25
4 313
5 1401
6 15681
7 90609
8 909945
9 6105913
10 57290209
11 421304049
12 3799765201
13 29595440785
14 261111392985
15 2109792275145
16 18400232046585
17 152275971653625
18 1320864136716225
19 11107129707193809
20 96160509723165393
21 817518139811725713
22 7077960886109335737
23 60642227399014653225

List of values

[1, 9, 25, 313, 1401, 15681, 90609, 909945, 6105913, 57290209, 421304049, 3799765201, 29595440785, 261111392985, 2109792275145, 18400232046585, 152275971653625, 1320864136716225, 11107129707193809, 96160509723165393, 817518139811725713, 7077960886109335737, 60642227399014653225]

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

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