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 | 3 |
| 3 | 11 |
| 4 | 65 |
| 5 | 411 |
| 6 | 3535 |
| 7 | 31081 |
| 8 | 337185 |
| 9 | 3846557 |
| 10 | 50329253 |
| 11 | 691740489 |
| 12 | 10725769171 |
| 13 | 172411994899 |
| 14 | 3050277039465 |
| 15 | 56428854605627 |
| 16 | 1124781474310649 |
| 17 | 23349607769846667 |
| 18 | 518744693882444419 |
| 19 | 11949343411110856153 |
| 20 | 291921874093876965453 |
| 21 | 7395266131906154621501 |