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.

A262233 Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=1 if n>0.

Table of values

n a(n)
0 1
1 1
2 1
3 3
4 20
5 220
6 3648
7 84616
8 2617696
9 104112576
10 5176135040
11 314525766016
12 22934467613184
13 1976385358538240
14 198701625441195520
15 23050434113386398720
16 3055967615464202301440
17 459172688072604359835648
18 77616824553405653653094400

List of values

[1, 1, 1, 3, 20, 220, 3648, 84616, 2617696, 104112576, 5176135040, 314525766016, 22934467613184, 1976385358538240, 198701625441195520, 23050434113386398720, 3055967615464202301440, 459172688072604359835648, 77616824553405653653094400]

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

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