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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.

A278883 a(n) = (4*n+1) * ( binomial(3*n,n)/(2*n+1) )^2.

Table of values

n a(n)
0 1
1 5
2 81
3 1872
4 51425
5 1565109
6 50979600
7 1742711616
8 61765676577
9 2251396558125
10 83924761860225
11 3186277484832000
12 122829049870699536
13 4796448751641900752
14 189381233826675892800
15 7549371503605704934656
16 303473219026059360959265
17 12289574902507266828093525
18 500960076377670398672062425
19 20540854991655352005504930000
20 846696245823312839372671355025
21 35068049224094584278339245227125
22 1458752047374053912228252043321600

List of values

[1, 5, 81, 1872, 51425, 1565109, 50979600, 1742711616, 61765676577, 2251396558125, 83924761860225, 3186277484832000, 122829049870699536, 4796448751641900752, 189381233826675892800, 7549371503605704934656, 303473219026059360959265, 12289574902507266828093525, 500960076377670398672062425, 20540854991655352005504930000, 846696245823312839372671355025, 35068049224094584278339245227125, 1458752047374053912228252043321600]

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

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