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 | 4 |
| 2 | 19 |
| 3 | 173 |
| 4 | 1860 |
| 5 | 21814 |
| 6 | 271388 |
| 7 | 3515330 |
| 8 | 46906860 |
| 9 | 640321565 |
| 10 | 8899950644 |
| 11 | 125524292790 |
| 12 | 1791943900656 |
| 13 | 25843064347685 |
| 14 | 375956017001280 |
| 15 | 5510454405453368 |
| 16 | 81297696816798684 |
| 17 | 1206334991431968912 |
| 18 | 17991734573723974384 |
| 19 | 269560224872407933010 |