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 | 6 |
| 4 | 35 |
| 5 | 349 |
| 6 | 3766 |
| 7 | 45632 |
| 8 | 580203 |
| 9 | 7687128 |
| 10 | 104898024 |
| 11 | 1466605630 |
| 12 | 20916933674 |
| 13 | 303368072539 |
| 14 | 4463328542008 |
| 15 | 66484512715040 |
| 16 | 1001084180891355 |
| 17 | 15217675702394661 |
| 18 | 233285495922344929 |
| 19 | 3603276856175739600 |
| 20 | 56033315904277236728 |
| 21 | 876698296980033411125 |