cp's OEIS Frontend

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.

A161217 a(n) = Sum_{d|n} phi(n/d)^2*2^(d+1).

Table of values

n a(n)
0 0
1 4
2 12
3 32
4 56
5 128
6 192
7 400
8 640
9 1232
10 2304
11 4496
12 8608
13 16960
14 33456
15 66304
16 132096
17 263168
18 526320
19 1049872
20 2100352
21 4196480
22 8393904
23 16779152
24 33565952
25 67111488
26 134235840
27 268441424
28 536906720
29 1073744960
30 2147560704
31 4294970896
32 8590069760

List of values

[0, 4, 12, 32, 56, 128, 192, 400, 640, 1232, 2304, 4496, 8608, 16960, 33456, 66304, 132096, 263168, 526320, 1049872, 2100352, 4196480, 8393904, 16779152, 33565952, 67111488, 134235840, 268441424, 536906720, 1073744960, 2147560704, 4294970896, 8590069760]