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 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 34 |
| 6 | 156 |
| 7 | 1044 |
| 8 | 12346 |
| 9 | 274668 |
| 10 | 12005168 |
| 11 | 1018997864 |
| 12 | 165091172592 |
| 13 | 50502031367952 |
| 14 | 29054155657235488 |
| 15 | 31426485969804308768 |
| 16 | 64001015704527557894928 |
| 17 | 245935864153532932683719776 |
| 18 | 1787577725145611700547878190848 |
| 19 | 24637809253125004524383007491432768 |