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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.

A340993 a(n) is the (2n)-th term of the n-fold self-convolution of the sum of divisors function sigma.

Table of values

n a(n)
0 1
1 3
2 17
3 120
4 885
5 6713
6 51932
7 407214
8 3224845
9 25733325
10 206584437
11 1666561042
12 13498994796
13 109713432390
14 894291885000
15 7307812510970
16 59847327807597
17 491062976039618
18 4036174402666925
19 33224883837921930
20 273873806179142545
21 2260338391869532332

List of values

[1, 3, 17, 120, 885, 6713, 51932, 407214, 3224845, 25733325, 206584437, 1666561042, 13498994796, 109713432390, 894291885000, 7307812510970, 59847327807597, 491062976039618, 4036174402666925, 33224883837921930, 273873806179142545, 2260338391869532332]

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

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