cp's OEIS Frontend

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.

A229421 Number of n X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, rows lexicographically nondecreasing, and columns lexicographically nonincreasing.

Table of values

n a(n)
1 3
2 12
3 83
4 754
5 7816
6 87648
7 1037193
8 12768612
9 162034856
10 2106287556
11 27919532994
12 376116911288
13 5136301331502
14 70961712401226
15 990271481453131
16 13940677426765198
17 197768065242681646
18 2824828320413979786
19 40595088421065998006
20 586585037559246948950

List of values

[3, 12, 83, 754, 7816, 87648, 1037193, 12768612, 162034856, 2106287556, 27919532994, 376116911288, 5136301331502, 70961712401226, 990271481453131, 13940677426765198, 197768065242681646, 2824828320413979786, 40595088421065998006, 586585037559246948950]

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

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