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 | 5 |
| 2 | 51 |
| 3 | 260 |
| 4 | 2651 |
| 5 | 13515 |
| 6 | 137801 |
| 7 | 702520 |
| 8 | 7163001 |
| 9 | 36517525 |
| 10 | 372338251 |
| 11 | 1898208780 |
| 12 | 19354426051 |
| 13 | 98670339035 |
| 14 | 1006057816401 |
| 15 | 5128959421040 |
| 16 | 52295652026801 |
| 17 | 266607219555045 |
| 18 | 2718367847577251 |
| 19 | 13858446457441300 |