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 | 5 |
| 2 | 18 |
| 3 | 66 |
| 4 | 280 |
| 5 | 1420 |
| 6 | 8544 |
| 7 | 59836 |
| 8 | 478720 |
| 9 | 4308516 |
| 10 | 43085200 |
| 11 | 473937244 |
| 12 | 5687246976 |
| 13 | 73934210740 |
| 14 | 1035078950416 |
| 15 | 15526184256300 |
| 16 | 248418948100864 |
| 17 | 4223122117714756 |
| 18 | 76016198118865680 |
| 19 | 1444307764258447996 |