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.

A278628 Number of nX2 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.

Table of values

n a(n)
1 0
2 13
3 285
4 3354
5 27521
6 175881
7 932205
8 4266912
9 17344954
10 63898594
11 216606040
12 683599110
13 2027209742
14 5691010421
15 15216367989
16 38944866772
17 95817126997
18 227430633270
19 522402290790
20 1164311022921
21 2523775686270
22 5331359865045

List of values

[0, 13, 285, 3354, 27521, 175881, 932205, 4266912, 17344954, 63898594, 216606040, 683599110, 2027209742, 5691010421, 15216367989, 38944866772, 95817126997, 227430633270, 522402290790, 1164311022921, 2523775686270, 5331359865045]

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

Content is available under The OEIS End-User License Agreement.