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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.

A228158 Numbers n such that the cardinality of (natural numbers <=n with a first digit of 1) = n/2.

Table of values

n a(n)
1 2
2 16
3 22
4 176
5 222
6 1776
7 2222
8 17776
9 22222
10 177776
11 222222
12 1777776
13 2222222
14 17777776
15 22222222
16 177777776
17 222222222
18 1777777776
19 2222222222
20 17777777776
21 22222222222
22 177777777776
23 222222222222
24 1777777777776
25 2222222222222
26 17777777777776

List of values

[2, 16, 22, 176, 222, 1776, 2222, 17776, 22222, 177776, 222222, 1777776, 2222222, 17777776, 22222222, 177777776, 222222222, 1777777776, 2222222222, 17777777776, 22222222222, 177777777776, 222222222222, 1777777777776, 2222222222222, 17777777777776]

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

Content is available under The OEIS End-User License Agreement.