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 | 1 |
| 3 | 13 |
| 4 | 49 |
| 5 | 481 |
| 6 | 3841 |
| 7 | 38221 |
| 8 | 464353 |
| 9 | 5368609 |
| 10 | 82042561 |
| 11 | 1151767981 |
| 12 | 20242097041 |
| 13 | 342921513793 |
| 14 | 6705416722369 |
| 15 | 133590317946541 |
| 16 | 2880298682358721 |
| 17 | 65597610230669761 |
| 18 | 1556262483879791233 |
| 19 | 39569880403136366029 |
| 20 | 1030778206965403668721 |