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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 99 |
| 5 | 724 |
| 6 | 4820 |
| 7 | 33381 |
| 8 | 227862 |
| 9 | 1564198 |
| 10 | 10714823 |
| 11 | 73457064 |
| 12 | 503438760 |
| 13 | 3450734281 |
| 14 | 23651386922 |
| 15 | 162109796922 |
| 16 | 1111115037483 |
| 17 | 7615701104764 |
| 18 | 52198777931900 |
| 19 | 357775783071021 |
| 20 | 2452231602371646 |
| 21 | 16807845698458702 |