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 | 4 |
| 2 | 29 |
| 3 | 261 |
| 4 | 2627 |
| 5 | 28315 |
| 6 | 319648 |
| 7 | 3731037 |
| 8 | 44663058 |
| 9 | 545312504 |
| 10 | 6764556591 |
| 11 | 85015779095 |
| 12 | 1080185111768 |
| 13 | 13852183882612 |
| 14 | 179058158369828 |
| 15 | 2330621446075640 |
| 16 | 30519758687849439 |
| 17 | 401806204894374041 |
| 18 | 5315243189757111099 |
| 19 | 70613088335938995385 |
| 20 | 941714812929017751855 |