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.

A049221 Number of horizontally convex n-ominoes in which the top row has exactly 1 square, which is not above the rightmost square in the second row.

Table of values

n a(n)
1 1
2 0
3 1
4 4
5 14
6 46
7 148
8 474
9 1518
10 4864
11 15590
12 49974
13 160196
14 513522
15 1646134
16 5276800
17 16915150
18 54222686
19 173814580
20 557174698
21 1786062174
22 5725346304
23 18352995094
24 58831800038
25 188589419748
26 604536478850
27 1937883656166

List of values

[1, 0, 1, 4, 14, 46, 148, 474, 1518, 4864, 15590, 49974, 160196, 513522, 1646134, 5276800, 16915150, 54222686, 173814580, 557174698, 1786062174, 5725346304, 18352995094, 58831800038, 188589419748, 604536478850, 1937883656166]

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

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