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 | 4 |
| 2 | 23 |
| 3 | 28 |
| 4 | 491 |
| 5 | 1249 |
| 6 | 19223 |
| 7 | 15476 |
| 8 | 3515161 |
| 9 | 1512661 |
| 10 | 14496817 |
| 11 | 228800107 |
| 12 | 11770539419 |
| 13 | 60428965661 |
| 14 | 5262254717509 |
| 15 | 2521163372543 |
| 16 | 976843770850217 |
| 17 | 887131806309703 |
| 18 | 73511154681979031 |
| 19 | 255777165814872577 |