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 | 10 |
| 3 | 50 |
| 4 | 570 |
| 5 | 4450 |
| 6 | 56202 |
| 7 | 501970 |
| 8 | 6676410 |
| 9 | 63799490 |
| 10 | 875391370 |
| 11 | 8715058802 |
| 12 | 122088479930 |
| 13 | 1249437863970 |
| 14 | 17764858122250 |
| 15 | 185445650940690 |
| 16 | 2666213981716282 |
| 17 | 28252030821781890 |
| 18 | 409717783914784010 |