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.

A217805 Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).

Table of values

n a(n)
1 1
2 5
3 42
4 444
5 5337
6 69657
7 962939
8 13890083
9 207042035

List of values

[1, 5, 42, 444, 5337, 69657, 962939, 13890083, 207042035]