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 | 30 |
| 2 | 450 |
| 3 | 4510 |
| 4 | 34050 |
| 5 | 207006 |
| 6 | 1057730 |
| 7 | 4680990 |
| 8 | 18347010 |
| 9 | 64797470 |
| 10 | 209070018 |
| 11 | 623207070 |
| 12 | 1732242690 |
| 13 | 4524812190 |
| 14 | 11180805570 |
| 15 | 26283115038 |
| 16 | 59064045570 |
| 17 | 127421652510 |
| 18 | 264870794690 |
| 19 | 532225891230 |
| 20 | 1036722552066 |