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) |
|---|---|
| 1 | 4 |
| 2 | 24 |
| 3 | 99 |
| 4 | 599 |
| 5 | 2474 |
| 6 | 14974 |
| 7 | 61849 |
| 8 | 374349 |
| 9 | 1546224 |
| 10 | 9358724 |
| 11 | 38655599 |
| 12 | 233968099 |
| 13 | 966389974 |
| 14 | 5849202474 |
| 15 | 24159749349 |
| 16 | 146230061849 |
| 17 | 603993733724 |
| 18 | 3655751546224 |
| 19 | 15099843343099 |
| 20 | 91393788655599 |
| 21 | 377496083577474 |