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.

A360421 a(n) = the number of X-frame polyominoes with n cells, reduced for symmetry.

Table of values

n a(n)
1 0
2 0
3 0
4 0
5 1
6 2
7 7
8 20
9 49
10 109
11 216
12 414
13 723
14 1228
15 1958
16 3065
17 4580
18 6734

List of values

[0, 0, 0, 0, 1, 2, 7, 20, 49, 109, 216, 414, 723, 1228, 1958, 3065, 4580, 6734]