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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.

A308521 Expansion of e.g.f. (sec(x) + tan(x))/(1 - 2*x).

Table of values

n a(n)
0 1
1 3
2 13
3 80
4 645
5 6466
6 77653
7 1087414
8 17400009
9 313208098
10 6264212481
11 137813028374
12 3307515383741
13 85995422345522
14 2407872025035597
15 72236162654825222
16 2311557224345919249
17 78592945837626597442
18 2829346052559437183353
19 107515150026347498080246

List of values

[1, 3, 13, 80, 645, 6466, 77653, 1087414, 17400009, 313208098, 6264212481, 137813028374, 3307515383741, 85995422345522, 2407872025035597, 72236162654825222, 2311557224345919249, 78592945837626597442, 2829346052559437183353, 107515150026347498080246]

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

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