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 | 2 |
| 2 | 7 |
| 3 | 34 |
| 4 | 221 |
| 5 | 1666 |
| 6 | 15187 |
| 7 | 153602 |
| 8 | 1770169 |
| 9 | 22379266 |
| 10 | 312164831 |
| 11 | 4685997922 |
| 12 | 76668261397 |
| 13 | 1335425319554 |
| 14 | 24921410400811 |
| 15 | 493075754663746 |
| 16 | 10358312736025457 |
| 17 | 228862423291312642 |
| 18 | 5335861084579488439 |
| 19 | 130235118120543955106 |
| 20 | 3333808742649699747661 |