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.

A162978 Number of fixed points in all alternating (i.e., down-up) permutations of {1,2,...,n}.

Table of values

n a(n)
1 1
2 0
3 1
4 4
5 15
6 52
7 257
8 1272
9 7679
10 47864
11 346113
12 2604380
13 22022143
14 194053836
15 1881735169
16 18998097328
17 207983607807
18 2366490065968
19 28880901505025
20 365599818496116
21 4922617151619071
22 68612903386404260
23 1010501269355233281
24 15376572385777544744

List of values

[1, 0, 1, 4, 15, 52, 257, 1272, 7679, 47864, 346113, 2604380, 22022143, 194053836, 1881735169, 18998097328, 207983607807, 2366490065968, 28880901505025, 365599818496116, 4922617151619071, 68612903386404260, 1010501269355233281, 15376572385777544744]

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

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