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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.

A370509 Expansion of Sum_{k>=0} k! * ( x * (1+x^2) )^k.

Table of values

n a(n)
0 1
1 1
2 2
3 7
4 28
5 138
6 818
7 5658
8 44784
9 399366
10 3962256
11 43289760
12 516432984
13 6679346280
14 93091875120
15 1390851720840
16 22175338353120
17 375794883339120
18 6745177713093840
19 127830886641354960
20 2550687440585679360
21 53451172032327664560
22 1173650135526055272960

List of values

[1, 1, 2, 7, 28, 138, 818, 5658, 44784, 399366, 3962256, 43289760, 516432984, 6679346280, 93091875120, 1390851720840, 22175338353120, 375794883339120, 6745177713093840, 127830886641354960, 2550687440585679360, 53451172032327664560, 1173650135526055272960]

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

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