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 | 1 |
| 2 | 5 |
| 3 | 35 |
| 4 | 310 |
| 5 | 2980 |
| 6 | 30526 |
| 7 | 325655 |
| 8 | 3581200 |
| 9 | 40301850 |
| 10 | 461925625 |
| 11 | 5373527605 |
| 12 | 63281397830 |
| 13 | 752962948360 |
| 14 | 9038406399150 |
| 15 | 109321688626100 |
| 16 | 1331047556550240 |
| 17 | 16300720361555725 |
| 18 | 200658900798443135 |
| 19 | 2481460407963908510 |
| 20 | 30814094488256704650 |
| 21 | 384069865485447909905 |