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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.

A318638 Expansion of Sum_{n>=1} ( (3 + x^n)^n - 3^n ).

Table of values

n a(n)
1 1
2 6
3 27
4 109
5 405
6 1467
7 5103
8 17550
9 59050
10 197100
11 649539
12 2126991
13 6908733
14 22325625
15 71744625
16 229602925
17 731794257
18 2324602206
19 7360989291
20 23245524600
21 73222475256
22 230128853031
23 721764371007
24 2259440202825
25 7060738412026
26 22029517662984
27 68630377426119
28 213516777941712
29 663426981193869
30 2058911488612863
31 6382625094934119
32 19765549255048254
33 61149666233193318

List of values

[1, 6, 27, 109, 405, 1467, 5103, 17550, 59050, 197100, 649539, 2126991, 6908733, 22325625, 71744625, 229602925, 731794257, 2324602206, 7360989291, 23245524600, 73222475256, 230128853031, 721764371007, 2259440202825, 7060738412026, 22029517662984, 68630377426119, 213516777941712, 663426981193869, 2058911488612863, 6382625094934119, 19765549255048254, 61149666233193318]

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

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