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.

A193777 Number of signed permutations of size 2n invariant under D and D'bar and avoiding (-2, 1) and (2, -1).

Table of values

n a(n)
0 1
1 2
2 6
3 18
4 58
5 190
6 642
7 2206
8 7746
9 27662
10 100738
11 373550
12 1413506
13 5457710
14 21546466
15 87025806
16 360264258
17 1529624366
18 6669850466
19 29877013902
20 137560725890
21 650780790894
22 3162711095074
23 15774862353614
24 80687636530882
25 422713072650286
26 2265833731786594

List of values

[1, 2, 6, 18, 58, 190, 642, 2206, 7746, 27662, 100738, 373550, 1413506, 5457710, 21546466, 87025806, 360264258, 1529624366, 6669850466, 29877013902, 137560725890, 650780790894, 3162711095074, 15774862353614, 80687636530882, 422713072650286, 2265833731786594]

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

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