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 | 5 |
| 2 | 49 |
| 3 | 449 |
| 4 | 3841 |
| 5 | 31745 |
| 6 | 258049 |
| 7 | 2080769 |
| 8 | 16711681 |
| 9 | 133955585 |
| 10 | 1072693249 |
| 11 | 8585740289 |
| 12 | 68702699521 |
| 13 | 549688705025 |
| 14 | 4397778075649 |
| 15 | 35183298347009 |
| 16 | 281470681743361 |
| 17 | 2251782633816065 |
| 18 | 18014329790005249 |
| 19 | 144114913197948929 |
| 20 | 1152920405095219201 |
| 21 | 9223367638808264705 |