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 | 10 |
| 3 | 68 |
| 4 | 618 |
| 5 | 6352 |
| 6 | 71188 |
| 7 | 841332 |
| 8 | 10352618 |
| 9 | 131328068 |
| 10 | 1706742160 |
| 11 | 22619741212 |
| 12 | 304685855700 |
| 13 | 4160480013848 |
| 14 | 57476485976388 |
| 15 | 802048167035968 |
| 16 | 11290551106506218 |
| 17 | 160168176177137896 |
| 18 | 2287724464324213972 |