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.

A173426 a(n) is obtained by starting with 1, sequentially concatenating all decimal numbers up to n, and then, starting from n-1, sequentially concatenating all decimal numbers down to 1.

Table of values

n a(n)
1 1
2 121
3 12321
4 1234321
5 123454321
6 12345654321
7 1234567654321
8 123456787654321
9 12345678987654321
10 12345678910987654321
11 123456789101110987654321
12 1234567891011121110987654321
13 12345678910111213121110987654321
14 123456789101112131413121110987654321

List of values

[1, 121, 12321, 1234321, 123454321, 12345654321, 1234567654321, 123456787654321, 12345678987654321, 12345678910987654321, 123456789101110987654321, 1234567891011121110987654321, 12345678910111213121110987654321, 123456789101112131413121110987654321]

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

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