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 | 1 |
| 2 | 31 |
| 3 | 206 |
| 4 | 1181 |
| 5 | 10639 |
| 6 | 90727 |
| 7 | 720785 |
| 8 | 5909241 |
| 9 | 48847911 |
| 10 | 400405024 |
| 11 | 3283795151 |
| 12 | 26976077016 |
| 13 | 221488948284 |
| 14 | 1818161928153 |
| 15 | 14927447103567 |
| 16 | 122557391321622 |
| 17 | 1006185363901356 |
| 18 | 8260764995494461 |
| 19 | 67821099419523837 |
| 20 | 556811248211302092 |