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 | 9 |
| 3 | 29 |
| 4 | 99 |
| 5 | 351 |
| 6 | 1275 |
| 7 | 4707 |
| 8 | 17577 |
| 9 | 66197 |
| 10 | 250953 |
| 11 | 956385 |
| 12 | 3660541 |
| 13 | 14061141 |
| 14 | 54177741 |
| 15 | 209295261 |
| 16 | 810375651 |
| 17 | 3143981871 |
| 18 | 12219117171 |
| 19 | 47564380971 |
| 20 | 185410909791 |
| 21 | 723668784231 |
| 22 | 2827767747951 |
| 23 | 11061198475551 |
| 24 | 43308802158651 |
| 25 | 169719408596403 |
| 26 | 665637941544507 |