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 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 117 |
| 4 | 1866 |
| 5 | 32553 |
| 6 | 603414 |
| 7 | 11654634 |
| 8 | 232034283 |
| 9 | 4728048201 |
| 10 | 98125181461 |
| 11 | 2066983603704 |
| 12 | 44079196497075 |
| 13 | 949772378078829 |
| 14 | 20645820782745363 |
| 15 | 452215682045713701 |
| 16 | 9970925646977589555 |
| 17 | 221133330528834114000 |
| 18 | 4929622717525248345174 |
| 19 | 110400838255998014848137 |