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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.

A242903 G.f. A(x) satisfies: coefficient of x^n in A(x)^(2*n) equals A000172(n) = Sum_{k=0..n} C(n,k)^3, the n-th Franel number.

Table of values

n a(n)
0 1
1 1
2 1
3 1
4 3
5 8
6 26
7 89
8 324
9 1225
10 4786
11 19170
12 78408
13 326275
14 1377772
15 5891401
16 25467509
17 111144579
18 489145720
19 2168854885
20 9681072845
21 43473716527
22 196286934526
23 890640262188
24 4059500301390
25 18579693200838
26 85360357637580
27 393548515741979
28 1820335724153452
29 8445294476235727
30 39291407672079211

List of values

[1, 1, 1, 1, 3, 8, 26, 89, 324, 1225, 4786, 19170, 78408, 326275, 1377772, 5891401, 25467509, 111144579, 489145720, 2168854885, 9681072845, 43473716527, 196286934526, 890640262188, 4059500301390, 18579693200838, 85360357637580, 393548515741979, 1820335724153452, 8445294476235727, 39291407672079211]

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

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