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 | 12 |
| 3 | 57 |
| 4 | 309 |
| 5 | 1866 |
| 6 | 12351 |
| 7 | 88563 |
| 8 | 681870 |
| 9 | 5597643 |
| 10 | 48718569 |
| 11 | 447428856 |
| 12 | 4318854429 |
| 13 | 43666895343 |
| 14 | 461101962108 |
| 15 | 5072054649573 |
| 16 | 57986312752497 |
| 17 | 687610920335610 |
| 18 | 8442056059773267 |
| 19 | 107135148331162767 |
| 20 | 1403300026585387686 |
| 21 | 18946012544520590991 |