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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.

A137287 a(n) is the number 2 written (prime(n)-1)/2 times followed by the digit 1; a(1)=2.

Table of values

n a(n)
1 2
2 21
3 221
4 2221
5 222221
6 2222221
7 222222221
8 2222222221
9 222222222221
10 222222222222221
11 2222222222222221
12 2222222222222222221
13 222222222222222222221
14 2222222222222222222221
15 222222222222222222222221
16 222222222222222222222222221
17 222222222222222222222222222221

List of values

[2, 21, 221, 2221, 222221, 2222221, 222222221, 2222222221, 222222222221, 222222222222221, 2222222222222221, 2222222222222222221, 222222222222222222221, 2222222222222222222221, 222222222222222222222221, 222222222222222222222222221, 222222222222222222222222222221]

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

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