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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.

A005768 Number of convex polygons of length 2n on square lattice whose leftmost bottom vertex is strictly to the left of the rightmost top vertex.

Table of values

n a(n)
2 1
3 2
4 7
5 27
6 110
7 460
8 1948
9 8296
10 35400
11 151056
12 643892
13 2740216
14 11639416
15 49340080
16 208727176
17 881212272
18 3713043152
19 15615663008
20 65555425780
21 274734294328
22 1149506252376
23 4802212126704
24 20032666552664
25 83452195924304
26 347192769717040
27 1442672957396320

List of values

[1, 2, 7, 27, 110, 460, 1948, 8296, 35400, 151056, 643892, 2740216, 11639416, 49340080, 208727176, 881212272, 3713043152, 15615663008, 65555425780, 274734294328, 1149506252376, 4802212126704, 20032666552664, 83452195924304, 347192769717040, 1442672957396320]

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

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