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 | 5 |
| 2 | 30 |
| 3 | 166 |
| 4 | 915 |
| 5 | 5032 |
| 6 | 27680 |
| 7 | 152243 |
| 8 | 837339 |
| 9 | 4605366 |
| 10 | 25329516 |
| 11 | 139312339 |
| 12 | 766217865 |
| 13 | 4214198259 |
| 14 | 23178090428 |
| 15 | 127479497357 |
| 16 | 701137235467 |
| 17 | 3856254795069 |
| 18 | 21209401372879 |
| 19 | 116651707550839 |
| 20 | 641584391529617 |