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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.

A217661 G.f.: Sum_{n>=0} x^n * Sum_{k=0..n} binomial(n,k)^2 * x^k/(1-x)^k.

Table of values

n a(n)
0 1
1 1
2 2
3 6
4 16
5 42
6 114
7 314
8 870
9 2426
10 6804
11 19168
12 54198
13 153730
14 437232
15 1246480
16 3560838
17 10190810
18 29212432
19 83860176
20 241051796
21 693709896
22 1998535892
23 5763312876
24 16635018146
25 48054500898
26 138923916700
27 401908892716
28 1163493516356
29 3370283517032

List of values

[1, 1, 2, 6, 16, 42, 114, 314, 870, 2426, 6804, 19168, 54198, 153730, 437232, 1246480, 3560838, 10190810, 29212432, 83860176, 241051796, 693709896, 1998535892, 5763312876, 16635018146, 48054500898, 138923916700, 401908892716, 1163493516356, 3370283517032]

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

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