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 | 9 |
| 4 | 52 |
| 5 | 405 |
| 6 | 3786 |
| 7 | 42301 |
| 8 | 542984 |
| 9 | 7924041 |
| 10 | 129110230 |
| 11 | 2327399481 |
| 12 | 45940938924 |
| 13 | 986045445853 |
| 14 | 22856850513602 |
| 15 | 569163515043285 |
| 16 | 15150885843083536 |
| 17 | 429364157810169105 |
| 18 | 12905794670246364078 |
| 19 | 410108007771441394129 |
| 20 | 13736898888997174964660 |
| 21 | 483740530150449507164901 |
| 22 | 17866185834825657429606682 |