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 | 3 |
| 2 | 9 |
| 3 | 30 |
| 4 | 117 |
| 5 | 528 |
| 6 | 2709 |
| 7 | 15600 |
| 8 | 99657 |
| 9 | 699648 |
| 10 | 5355009 |
| 11 | 44382720 |
| 12 | 396019197 |
| 13 | 3785146368 |
| 14 | 38583663309 |
| 15 | 417826928640 |
| 16 | 4790367838737 |
| 17 | 57967904882688 |
| 18 | 738337496799609 |
| 19 | 9873907221135360 |
| 20 | 138327377598038277 |
| 21 | 2025896274960580608 |
| 22 | 30959719452721035909 |
| 23 | 492827536493909114880 |