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.

A278621 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake.

Table of values

n a(n)
1 3
2 46
3 357
4 1952
5 8518
6 31605
7 103546
8 307087
9 838936
10 2138608
11 5137407
12 11719956
13 25549096
14 53493458
15 108027996
16 211167710
17 400765157
18 740380790
19 1334456849
20 2351234708
21 4056807390
22 6864961455
23 11409118950
24 18644841765
25 29994129570

List of values

[3, 46, 357, 1952, 8518, 31605, 103546, 307087, 838936, 2138608, 5137407, 11719956, 25549096, 53493458, 108027996, 211167710, 400765157, 740380790, 1334456849, 2351234708, 4056807390, 6864961455, 11409118950, 18644841765, 29994129570]