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 | 42 |
| 3 | 402 |
| 4 | 4070 |
| 5 | 42510 |
| 6 | 452900 |
| 7 | 4891988 |
| 8 | 53376966 |
| 9 | 586921790 |
| 10 | 6493225772 |
| 11 | 72192371100 |
| 12 | 805935279708 |
| 13 | 9028253155628 |
| 14 | 101433497725320 |
| 15 | 1142504966609512 |
| 16 | 12897113121607750 |
| 17 | 145870996300613406 |
| 18 | 1652690392388658012 |
| 19 | 18753389068268792780 |
| 20 | 213091273336786301940 |