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 | 3 |
| 2 | 9 |
| 3 | 39 |
| 4 | 249 |
| 5 | 2559 |
| 6 | 32589 |
| 7 | 543099 |
| 8 | 10242789 |
| 9 | 233335659 |
| 10 | 6703028889 |
| 11 | 207263519019 |
| 12 | 7628001653829 |
| 13 | 311878265181039 |
| 14 | 13394639596851069 |
| 15 | 628284422185342479 |
| 16 | 33217442899375387209 |
| 17 | 1955977793053588026279 |
| 18 | 119244359152460559009549 |
| 19 | 7977565910232727614888639 |