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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 23 |
| 5 | 69 |
| 6 | 203 |
| 7 | 601 |
| 8 | 1815 |
| 9 | 5493 |
| 10 | 16731 |
| 11 | 51225 |
| 12 | 157367 |
| 13 | 485093 |
| 14 | 1499499 |
| 15 | 4646233 |
| 16 | 14427095 |
| 17 | 44880981 |
| 18 | 139849979 |
| 19 | 436419737 |
| 20 | 1363713015 |
| 21 | 4266417221 |
| 22 | 13362194571 |
| 23 | 41891406681 |
| 24 | 131452430999 |
| 25 | 412835452213 |
| 26 | 1297543367835 |