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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.

A099580 a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k-1) * 4^(k-1).

Table of values

n a(n)
0 0
1 0
2 1
3 1
4 9
5 13
6 65
7 117
8 441
9 909
10 2929
11 6565
12 19305
13 45565
14 126881
15 309141
16 833049
17 2069613
18 5467345
19 13745797
20 35877321
21 90860509
22 235418369
23 598860405
24 1544728185
25 3940169805
26 10135859761
27 25896538981
28 66507086889
29 170093242813

List of values

[0, 0, 1, 1, 9, 13, 65, 117, 441, 909, 2929, 6565, 19305, 45565, 126881, 309141, 833049, 2069613, 5467345, 13745797, 35877321, 90860509, 235418369, 598860405, 1544728185, 3940169805, 10135859761, 25896538981, 66507086889, 170093242813]

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

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