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 | 7 |
| 4 | 35 |
| 5 | 212 |
| 6 | 1421 |
| 7 | 10128 |
| 8 | 75724 |
| 9 | 593905 |
| 10 | 4927764 |
| 11 | 43884083 |
| 12 | 426665219 |
| 13 | 4591883867 |
| 14 | 54943702996 |
| 15 | 725753304587 |
| 16 | 10428313247758 |
| 17 | 160361700765626 |
| 18 | 2602492613187389 |
| 19 | 44111609147837212 |
| 20 | 775162479337156853 |
| 21 | 14049351313802046511 |
| 22 | 261640973700411314373 |