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 | 26 |
| 4 | 76 |
| 5 | 222 |
| 6 | 648 |
| 7 | 1892 |
| 8 | 5524 |
| 9 | 16128 |
| 10 | 47088 |
| 11 | 137480 |
| 12 | 401392 |
| 13 | 1171920 |
| 14 | 3421584 |
| 15 | 9989792 |
| 16 | 29166592 |
| 17 | 85155936 |
| 18 | 248624640 |
| 19 | 725894336 |
| 20 | 2119349824 |
| 21 | 6187737600 |
| 22 | 18065963520 |
| 23 | 52746101888 |
| 24 | 153999606016 |
| 25 | 449623342848 |
| 26 | 1312738101504 |
| 27 | 3832722100736 |
| 28 | 11190167090176 |
| 29 | 32671254584832 |