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.

A351616 Number of free polyominoes with 2n squares, having 180-degree rotational symmetry about a vertex of a square, and no other symmetry.

Table of values

n a(n)
1 0
2 0
3 1
4 2
5 12
6 43
7 174
8 657
9 2571
10 9911
11 38633
12 150437
13 588544
14 2306204
15 9061179
16 35665587
17 140648710
18 555514177
19 2197298561
20 8702439446
21 34506900216
22 136972867380
23 544237912916
24 2164377093376
25 8614630304437

List of values

[0, 0, 1, 2, 12, 43, 174, 657, 2571, 9911, 38633, 150437, 588544, 2306204, 9061179, 35665587, 140648710, 555514177, 2197298561, 8702439446, 34506900216, 136972867380, 544237912916, 2164377093376, 8614630304437]

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

Content is available under The OEIS End-User License Agreement.