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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.

A004731 a(0) = 1; thereafter a(n) = denominator of (n-2)!! / (n-1)!!.

Table of values

n a(n)
0 1
1 1
2 1
3 2
4 3
5 8
6 15
7 16
8 35
9 128
10 315
11 256
12 693
13 1024
14 3003
15 2048
16 6435
17 32768
18 109395
19 65536
20 230945
21 262144
22 969969
23 524288
24 2028117
25 4194304
26 16900975
27 8388608
28 35102025
29 33554432
30 145422675
31 67108864
32 300540195
33 2147483648
34 9917826435
35 4294967296
36 20419054425

List of values

[1, 1, 1, 2, 3, 8, 15, 16, 35, 128, 315, 256, 693, 1024, 3003, 2048, 6435, 32768, 109395, 65536, 230945, 262144, 969969, 524288, 2028117, 4194304, 16900975, 8388608, 35102025, 33554432, 145422675, 67108864, 300540195, 2147483648, 9917826435, 4294967296, 20419054425]

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

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