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 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2092 |
| 5 | 19864 |
| 6 | 195352 |
| 7 | 1970896 |
| 8 | 20275660 |
| 9 | 211823800 |
| 10 | 2240795848 |
| 11 | 23951289520 |
| 12 | 258255469816 |
| 13 | 2805534253552 |
| 14 | 30675477376432 |
| 15 | 337306474674592 |
| 16 | 3727578443380492 |
| 17 | 41376874025687032 |
| 18 | 461121792658583272 |
| 19 | 5157384457905440752 |
| 20 | 57869888433073055272 |
| 21 | 651266142688270063312 |
| 22 | 7349148747954997832272 |