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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.

A357785 a(n) = coefficient of x^n, n >= 1, in A(x) such that: A(x)^2 = A( x^2/(1 - 4*x - 4*x^2) ) * sqrt(1 - 4*x - 4*x^2).

Table of values

n a(n)
1 1
2 1
3 4
4 15
5 65
6 291
7 1356
8 6474
9 31555
10 156315
11 784924
12 3986534
13 20444676
14 105728100
15 550735400
16 2886924190
17 15217019595
18 80600822575
19 428766983300
20 2289637381800
21 12268642450420
22 65941128441080
23 355396218177760
24 1920215555772550
25 10398415258863275

List of values

[1, 1, 4, 15, 65, 291, 1356, 6474, 31555, 156315, 784924, 3986534, 20444676, 105728100, 550735400, 2886924190, 15217019595, 80600822575, 428766983300, 2289637381800, 12268642450420, 65941128441080, 355396218177760, 1920215555772550, 10398415258863275]

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

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