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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.

A387507 a(n) = Sum_{k=0..floor(n/3)} 2^k * binomial(n-2*k,k)^2.

Table of values

n a(n)
0 1
1 1
2 1
3 3
4 9
5 19
6 37
7 87
8 217
9 507
10 1157
11 2727
12 6553
13 15627
14 37077
15 88519
16 212569
17 510715
18 1226853
19 2952615
20 7120921
21 17192427
22 41538293
23 100458759
24 243211865
25 589313755
26 1428931333
27 3467193191
28 8418640793
29 20453853003
30 49722339861
31 120936710471

List of values

[1, 1, 1, 3, 9, 19, 37, 87, 217, 507, 1157, 2727, 6553, 15627, 37077, 88519, 212569, 510715, 1226853, 2952615, 7120921, 17192427, 41538293, 100458759, 243211865, 589313755, 1428931333, 3467193191, 8418640793, 20453853003, 49722339861, 120936710471]

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

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