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 | 1 |
| 3 | 4 |
| 4 | 26 |
| 5 | 239 |
| 6 | 2768 |
| 7 | 38267 |
| 8 | 611193 |
| 9 | 11040954 |
| 10 | 222241117 |
| 11 | 4929304517 |
| 12 | 119423079917 |
| 13 | 3137864557135 |
| 14 | 88884310756274 |
| 15 | 2700439386780586 |
| 16 | 87603920737623984 |
| 17 | 3022626187893726774 |
| 18 | 110534722263602544357 |
| 19 | 4270777627515614565004 |
| 20 | 173854104446646589718022 |
| 21 | 7437462737558953036993295 |