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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 56 |
| 6 | 333 |
| 7 | 2147 |
| 8 | 17456 |
| 9 | 158022 |
| 10 | 1604281 |
| 11 | 17863089 |
| 12 | 216774585 |
| 13 | 2844162968 |
| 14 | 40129498111 |
| 15 | 605894465441 |
| 16 | 9748493596584 |
| 17 | 166520626541070 |
| 18 | 3009885559478844 |
| 19 | 57397289146583917 |
| 20 | 1151666341035710396 |