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 | 27 |
| 4 | 80 |
| 5 | 238 |
| 6 | 708 |
| 7 | 2106 |
| 8 | 6264 |
| 9 | 18632 |
| 10 | 55420 |
| 11 | 164844 |
| 12 | 490320 |
| 13 | 1458432 |
| 14 | 4338032 |
| 15 | 12903256 |
| 16 | 38380080 |
| 17 | 114159600 |
| 18 | 339561936 |
| 19 | 1010009744 |
| 20 | 3004222720 |
| 21 | 8935908000 |
| 22 | 26579404800 |
| 23 | 79059090528 |
| 24 | 235157252096 |
| 25 | 699463310848 |