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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.

A027295 a(n) = Sum_{k=0..m-1} T(n,k) * T(n,k+1), where m=n for n=0,1 and m=floor((n+3)/2) for n >= 2, and T given by A026022.

Table of values

n a(n)
1 1
2 4
3 15
4 52
5 195
6 676
7 2555
8 8976
9 34098
10 121448
11 463067
12 1669340
13 6384287
14 23251620
15 89157557
16 327523680
17 1258803182
18 4658150520
19 17940605163
20 66803546472
21 257777882894
22 965023761064
23 3730202020650
24 14029655954272
25 54315578806820
26 205120107930192

List of values

[1, 4, 15, 52, 195, 676, 2555, 8976, 34098, 121448, 463067, 1669340, 6384287, 23251620, 89157557, 327523680, 1258803182, 4658150520, 17940605163, 66803546472, 257777882894, 965023761064, 3730202020650, 14029655954272, 54315578806820, 205120107930192]

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

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