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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.

A137697 a(n) = x(n) * 2^((n mod 2 - 1)/2), with x(n)=Sum(x(k)*x(n-k-1):0<=k x(0)=SQRT(2).

Table of values

n a(n)
0 1
1 2
2 4
3 20
4 56
5 336
6 1056
7 6864
8 22880
9 155584
10 537472
11 3762304
12 13312768
13 95091200
14 342328320
15 2481880320
16 9051563520
17 66378132480

List of values

[1, 2, 4, 20, 56, 336, 1056, 6864, 22880, 155584, 537472, 3762304, 13312768, 95091200, 342328320, 2481880320, 9051563520, 66378132480]

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

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