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 | 5 |
| 3 | 30 |
| 4 | 231 |
| 5 | 1958 |
| 6 | 17977 |
| 7 | 173525 |
| 8 | 1741630 |
| 9 | 18004327 |
| 10 | 190569292 |
| 11 | 2056148051 |
| 12 | 22540654445 |
| 13 | 250438925115 |
| 14 | 2814570987591 |
| 15 | 31946390696157 |
| 16 | 365749566870782 |
| 17 | 4219388528587095 |
| 18 | 49005643635237875 |
| 19 | 572612058898037559 |