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 | 3 |
| 2 | 14 |
| 3 | 76 |
| 4 | 435 |
| 5 | 2577 |
| 6 | 15678 |
| 7 | 97272 |
| 8 | 612126 |
| 9 | 3891890 |
| 10 | 24933292 |
| 11 | 160663328 |
| 12 | 1040074684 |
| 13 | 6759228932 |
| 14 | 44075916696 |
| 15 | 288289595968 |
| 16 | 1890894150707 |
| 17 | 12434303045721 |
| 18 | 81960791460442 |
| 19 | 541428229233012 |
| 20 | 3583843659376257 |