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 | 5 |
| 3 | 40 |
| 4 | 431 |
| 5 | 5886 |
| 6 | 96817 |
| 7 | 1862890 |
| 8 | 41043375 |
| 9 | 1018584610 |
| 10 | 28108489541 |
| 11 | 853617865134 |
| 12 | 28287119604955 |
| 13 | 1015630741097350 |
| 14 | 39273014068691145 |
| 15 | 1627118268024495586 |
| 16 | 71904849762914854703 |
| 17 | 3375959341815207350850 |
| 18 | 167810405947367539063885 |
| 19 | 8803814897608815310714270 |