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 | 144 |
| 3 | 540 |
| 4 | 2372 |
| 5 | 10480 |
| 6 | 47502 |
| 7 | 217898 |
| 8 | 1010012 |
| 9 | 4717872 |
| 10 | 22176074 |
| 11 | 104770058 |
| 12 | 497093834 |
| 13 | 2367032490 |
| 14 | 11306090072 |
| 15 | 54148325140 |
| 16 | 259942544940 |
| 17 | 1250461443632 |
| 18 | 6026490869130 |
| 19 | 29092178813042 |
| 20 | 140648250533742 |