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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 90 |
| 6 | 396 |
| 7 | 1833 |
| 8 | 8801 |
| 9 | 43441 |
| 10 | 219092 |
| 11 | 1124201 |
| 12 | 5850414 |
| 13 | 30805498 |
| 14 | 163824559 |
| 15 | 878655117 |
| 16 | 4747341879 |
| 17 | 25815026491 |
| 18 | 141173582016 |
| 19 | 775920816789 |
| 20 | 4283833709457 |
| 21 | 23746640019657 |
| 22 | 132116647765569 |
| 23 | 737485227605338 |
| 24 | 4129174120158569 |
| 25 | 23183379592361839 |