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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 60 |
| 5 | 416 |
| 6 | 2791 |
| 7 | 18296 |
| 8 | 118016 |
| 9 | 752008 |
| 10 | 4746341 |
| 11 | 29727472 |
| 12 | 185016612 |
| 13 | 1145415208 |
| 14 | 7059265827 |
| 15 | 43338407712 |
| 16 | 265168691392 |
| 17 | 1617656173824 |
| 18 | 9842665771649 |
| 19 | 59748291677832 |
| 20 | 361933688520940 |
| 21 | 2188328005246304 |
| 22 | 13208464812265559 |
| 23 | 79600379336505560 |
| 24 | 479025509574159232 |