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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.

A159553 a(n) = Sum_{k=0..n} binomial(n,k) * gcd(n,k).

Table of values

n a(n)
1 2
2 6
3 12
4 28
5 40
6 144
7 140
8 536
9 864
10 2560
11 2068
12 12720
13 8216
14 45192
15 78660
16 182832
17 131104
18 933984
19 524324
20 3698240
21 4890648
22 13345816
23 8388652
24 67390464
25 60129600
26 225470544
27 279938160
28 1032462256
29 536870968
30 5018059200

List of values

[2, 6, 12, 28, 40, 144, 140, 536, 864, 2560, 2068, 12720, 8216, 45192, 78660, 182832, 131104, 933984, 524324, 3698240, 4890648, 13345816, 8388652, 67390464, 60129600, 225470544, 279938160, 1032462256, 536870968, 5018059200]

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

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