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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.

A240172 O.g.f.: Sum_{n>=0} n! * x^n * (1+x)^n.

Table of values

n a(n)
0 1
1 1
2 3
3 10
4 44
5 234
6 1470
7 10656
8 87624
9 806280
10 8211000
11 91707120
12 1114793280
13 14653936080
14 207138844080
15 3133376225280
16 50508380361600
17 864341342363520
18 15650522186302080
19 298948657681094400
20 6007868689030387200
21 126719410500228268800
22 2799004485444175008000
23 64613640777996615782400

List of values

[1, 1, 3, 10, 44, 234, 1470, 10656, 87624, 806280, 8211000, 91707120, 1114793280, 14653936080, 207138844080, 3133376225280, 50508380361600, 864341342363520, 15650522186302080, 298948657681094400, 6007868689030387200, 126719410500228268800, 2799004485444175008000, 64613640777996615782400]

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

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