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 | 4 |
| 3 | 29 |
| 4 | 210 |
| 5 | 2116 |
| 6 | 25522 |
| 7 | 362832 |
| 8 | 6000276 |
| 9 | 113593688 |
| 10 | 2434603356 |
| 11 | 58523364604 |
| 12 | 1565365441708 |
| 13 | 46273309903536 |
| 14 | 1502773485741816 |
| 15 | 53336787604185656 |
| 16 | 2059209704215556448 |
| 17 | 86117458019804680576 |
| 18 | 3886421648246467359364 |
| 19 | 188615552477984650605744 |