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 | 7 |
| 2 | 55 |
| 3 | 439 |
| 4 | 3511 |
| 5 | 28087 |
| 6 | 224695 |
| 7 | 1797559 |
| 8 | 14380471 |
| 9 | 115043767 |
| 10 | 920350135 |
| 11 | 7362801079 |
| 12 | 58902408631 |
| 13 | 471219269047 |
| 14 | 3769754152375 |
| 15 | 30158033218999 |
| 16 | 241264265751991 |
| 17 | 1930114126015927 |
| 18 | 15440913008127415 |
| 19 | 123527304065019319 |
| 20 | 988218432520154551 |
| 21 | 7905747460161236407 |