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) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 35 |
| 3 | 252 |
| 4 | 1498 |
| 5 | 7602 |
| 6 | 36498 |
| 7 | 165600 |
| 8 | 713769 |
| 9 | 2957647 |
| 10 | 11850223 |
| 11 | 46111352 |
| 12 | 174956250 |
| 13 | 649284286 |
| 14 | 2362771938 |
| 15 | 8449241836 |
| 16 | 29744151416 |
| 17 | 103237104740 |
| 18 | 353744829032 |
| 19 | 1198001464940 |
| 20 | 4013905507150 |
| 21 | 13316690882670 |
| 22 | 43780154987030 |
| 23 | 142726581203640 |