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.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 20 |
| 4 | 200 |
| 5 | 219 |
| 6 | 261 |
| 7 | 2000 |
| 8 | 2234 |
| 9 | 2551 |
| 10 | 2613 |
| 11 | 20000 |
| 12 | 20604 |
| 13 | 200000 |
| 14 | 202885 |
| 15 | 205704 |
| 16 | 218354 |
| 17 | 2000000 |
| 18 | 2155139 |
| 19 | 2490266 |
| 20 | 2620486 |
| 21 | 20000000 |
| 22 | 25882353 |
| 23 | 200000000 |
| 24 | 205705704 |
| 25 | 2000000000 |
| 26 | 2094600194 |
| 27 | 20000000000 |
| 28 | 20102030400 |
| 29 | 20349812814 |
| 30 | 21572321960 |