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 | 0 |
| 3 | 2 |
| 4 | 6 |
| 5 | 18 |
| 6 | 50 |
| 7 | 146 |
| 8 | 426 |
| 9 | 1282 |
| 10 | 3810 |
| 11 | 11394 |
| 12 | 34082 |
| 13 | 102338 |
| 14 | 306658 |
| 15 | 919874 |
| 16 | 2759154 |
| 17 | 8276898 |
| 18 | 24828386 |
| 19 | 74484386 |
| 20 | 223444258 |
| 21 | 670326242 |
| 22 | 2010964770 |
| 23 | 6032902242 |
| 24 | 18098635298 |
| 25 | 54295809826 |
| 26 | 162887261410 |
| 27 | 488661978274 |
| 28 | 1465985458850 |
| 29 | 4397955924386 |