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.

A221624 Number of 2Xn arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row.

Table of values

n a(n)
1 1
2 3
3 27
4 410
5 10055
6 353654
7 17052210
8 1075295220
9 86037489675
10 8510611773950
11 1020010974544958
12 145633667181394028
13 24424236713657975558
14 4754016566455947216412
15 1062903928921857001102308

List of values

[1, 3, 27, 410, 10055, 353654, 17052210, 1075295220, 86037489675, 8510611773950, 1020010974544958, 145633667181394028, 24424236713657975558, 4754016566455947216412, 1062903928921857001102308]

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

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