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 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 10 |
| 5 | 24 |
| 6 | 50 |
| 7 | 120 |
| 8 | 270 |
| 9 | 640 |
| 10 | 1500 |
| 11 | 3600 |
| 12 | 8610 |
| 13 | 20880 |
| 14 | 50700 |
| 15 | 124024 |
| 16 | 304290 |
| 17 | 750120 |
| 18 | 1854400 |
| 19 | 4600200 |
| 20 | 11440548 |
| 21 | 28527320 |
| 22 | 71289000 |
| 23 | 178526880 |
| 24 | 447910470 |
| 25 | 1125750120 |
| 26 | 2833885800 |
| 27 | 7144449920 |
| 28 | 18036373140 |
| 29 | 45591631800 |
| 30 | 115381697740 |
| 31 | 292329067800 |