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 | 9 |
| 2 | 57 |
| 3 | 321 |
| 4 | 1713 |
| 5 | 8889 |
| 6 | 45417 |
| 7 | 230001 |
| 8 | 1158753 |
| 9 | 5820009 |
| 10 | 29178777 |
| 11 | 146130081 |
| 12 | 731358993 |
| 13 | 3658920729 |
| 14 | 18300980937 |
| 15 | 91524036561 |
| 16 | 457677578433 |
| 17 | 2288560079049 |
| 18 | 11443316955897 |
| 19 | 57218134461441 |
| 20 | 286095321353073 |
| 21 | 1430490553902969 |
| 22 | 7152494610927657 |
| 23 | 35762598578876721 |