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.

A283184 a(n) is the number of symmetric permutations (p(1),p(2),...,p(m)) of (1,2,...,m), m=2n or m=2n+1, with p(m+1-k) = m+1-p(k) for 1<=k<=m, such that adjacent numbers do not differ by 1. a(n) is also the number of point-symmetric arrangements of m non-attacking kings on an m X m board, with one in each row and column.

Table of values

n a(n)
0 1
1 0
2 2
3 14
4 122
5 1262
6 15466
7 219646
8 3551194
9 64431374
10 1296712778
11 28672204574
12 691007296954
13 18029138380846
14 506320912190506
15 15228632768870462
16 488405396197019546
17 16638380026019579726
18 600022595692147574794
19 22836184629309211495774
20 914717041435012519583098

List of values

[1, 0, 2, 14, 122, 1262, 15466, 219646, 3551194, 64431374, 1296712778, 28672204574, 691007296954, 18029138380846, 506320912190506, 15228632768870462, 488405396197019546, 16638380026019579726, 600022595692147574794, 22836184629309211495774, 914717041435012519583098]