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 | 2 |
| 2 | 9 |
| 3 | 46 |
| 4 | 314 |
| 5 | 3072 |
| 6 | 37641 |
| 7 | 603510 |
| 8 | 11148030 |
| 9 | 249327430 |
| 10 | 7040987792 |
| 11 | 216220333314 |
| 12 | 7895699690498 |
| 13 | 321315600822232 |
| 14 | 13770543972819903 |
| 15 | 644232544408157820 |
| 16 | 33954066516677635554 |
| 17 | 1994206929690480710244 |
| 18 | 121461036181617491970561 |
| 19 | 8111955386813996410196454 |
| 20 | 574814471423312085719652432 |