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.

A268306 The number of even permutations p of 1,2,...,n such that -1<=p(i)-i<=2 for i=1,2,...,n.

Table of values

n a(n)
1 1
2 1
3 2
4 4
5 7
6 12
7 22
8 41
9 75
10 137
11 252
12 464
13 853
14 1568
15 2884
16 5305
17 9757
18 17945
19 33006
20 60708
21 111659
22 205372
23 377738
24 694769
25 1277879
26 2350385
27 4323032
28 7951296
29 14624713
30 26899040
31 49475048
32 90998801
33 167372889
34 307846737
35 566218426

List of values

[1, 1, 2, 4, 7, 12, 22, 41, 75, 137, 252, 464, 853, 1568, 2884, 5305, 9757, 17945, 33006, 60708, 111659, 205372, 377738, 694769, 1277879, 2350385, 4323032, 7951296, 14624713, 26899040, 49475048, 90998801, 167372889, 307846737, 566218426]