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 | 0 |
| 1 | 3 |
| 2 | 39 |
| 3 | 387 |
| 4 | 3471 |
| 5 | 29643 |
| 6 | 246519 |
| 7 | 2019027 |
| 8 | 16386591 |
| 9 | 132264603 |
| 10 | 1063976199 |
| 11 | 8541106467 |
| 12 | 68475336111 |
| 13 | 548535110763 |
| 14 | 4391942995479 |
| 15 | 35153854510707 |
| 16 | 281322388820031 |
| 17 | 2251036874232123 |
| 18 | 18010583812216359 |
| 19 | 144096114589527747 |
| 20 | 1152826137175206351 |
| 21 | 9222895199696572683 |