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 | 45 |
| 4 | 488 |
| 5 | 7770 |
| 6 | 134461 |
| 7 | 2913994 |
| 8 | 67769386 |
| 9 | 1862487633 |
| 10 | 63473407780 |
| 11 | 2266783873440 |
| 12 | 95508217654131 |
| 13 | 4406526837238776 |
| 14 | 210850931948426737 |
| 15 | 10938149689908832133 |
| 16 | 635914633137982893475 |
| 17 | 40923887389117331715131 |
| 18 | 2705755577277227205802881 |