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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.

A383539 a(n) = Sum_{k=0..floor(n/3)} binomial(n-k,k)^2 * binomial(n-2*k,k).

Table of values

n a(n)
0 1
1 1
2 1
3 5
4 19
5 49
6 137
7 481
8 1645
9 5259
10 17309
11 59477
12 203931
13 693865
14 2384149
15 8277773
16 28797631
17 100312525
18 350891175
19 1232122535
20 4335809699
21 15287669469
22 54029225569
23 191351513905
24 678850904981
25 2412164275651
26 8584573648693
27 30595269827149

List of values

[1, 1, 1, 5, 19, 49, 137, 481, 1645, 5259, 17309, 59477, 203931, 693865, 2384149, 8277773, 28797631, 100312525, 350891175, 1232122535, 4335809699, 15287669469, 54029225569, 191351513905, 678850904981, 2412164275651, 8584573648693, 30595269827149]

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

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