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 | 5 |
| 2 | 15 |
| 3 | 45 |
| 4 | 165 |
| 5 | 629 |
| 6 | 2635 |
| 7 | 11165 |
| 8 | 48915 |
| 9 | 217045 |
| 10 | 976887 |
| 11 | 4438925 |
| 12 | 20346485 |
| 13 | 93900245 |
| 14 | 435970995 |
| 15 | 2034505661 |
| 16 | 9536767665 |
| 17 | 44878791365 |
| 18 | 211927736135 |
| 19 | 1003867701485 |
| 20 | 4768372070757 |
| 21 | 22706531350485 |
| 22 | 108372083629275 |
| 23 | 518301258916445 |