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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.

A278405 a(n) = Sum_{k=0..n} binomial(n,2k)^2*binomial(n-k,k).

Table of values

n a(n)
0 1
1 1
2 2
3 19
4 110
5 476
6 2477
7 15093
8 86830
9 485290
10 2826902
11 16857116
12 100034453
13 594833357
14 3574477090
15 21611465819
16 130955824174
17 796195223398
18 4860425688176
19 29760574848750
20 182655048136510
21 1123720751229858
22 6929124085148938
23 42811398244528788

List of values

[1, 1, 2, 19, 110, 476, 2477, 15093, 86830, 485290, 2826902, 16857116, 100034453, 594833357, 3574477090, 21611465819, 130955824174, 796195223398, 4860425688176, 29760574848750, 182655048136510, 1123720751229858, 6929124085148938, 42811398244528788]

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

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