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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 30 |
| 6 | 90 |
| 7 | 288 |
| 8 | 864 |
| 9 | 2647 |
| 10 | 7968 |
| 11 | 24084 |
| 12 | 72252 |
| 13 | 217467 |
| 14 | 652401 |
| 15 | 1958931 |
| 16 | 5877333 |
| 17 | 17637453 |
| 18 | 52912359 |
| 19 | 158754606 |
| 20 | 476263818 |
| 21 | 1428840972 |
| 22 | 4286528100 |
| 23 | 12859728804 |
| 24 | 38579186412 |
| 25 | 115738013592 |
| 26 | 347214043476 |
| 27 | 1041643435230 |
| 28 | 3124930353363 |
| 29 | 9374794990911 |