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 | 0 |
| 2 | 5 |
| 3 | 21 |
| 4 | 150 |
| 5 | 884 |
| 6 | 5513 |
| 7 | 33860 |
| 8 | 208756 |
| 9 | 1285694 |
| 10 | 7921082 |
| 11 | 48795589 |
| 12 | 300602292 |
| 13 | 1851824780 |
| 14 | 11407972817 |
| 15 | 70277580919 |
| 16 | 432937512858 |
| 17 | 2667065000212 |
| 18 | 16430167559715 |
| 19 | 101216282472118 |
| 20 | 623532037268338 |
| 21 | 3841202145282104 |