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 | 3 |
| 1 | 70 |
| 2 | 642 |
| 3 | 4055 |
| 4 | 20945 |
| 5 | 95372 |
| 6 | 398290 |
| 7 | 1561683 |
| 8 | 5836190 |
| 9 | 21001410 |
| 10 | 73300478 |
| 11 | 249476600 |
| 12 | 831342517 |
| 13 | 2720979140 |
| 14 | 8768966810 |
| 15 | 27881856697 |
| 16 | 87610794135 |
| 17 | 272424413508 |
| 18 | 839229287580 |
| 19 | 2563768831145 |
| 20 | 7773145679478 |