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 | 47 |
| 3 | 315 |
| 4 | 2111 |
| 5 | 14147 |
| 6 | 94807 |
| 7 | 635355 |
| 8 | 4257871 |
| 9 | 28534387 |
| 10 | 191224967 |
| 11 | 1281505995 |
| 12 | 8588092031 |
| 13 | 57553632227 |
| 14 | 385699241527 |
| 15 | 2584787426235 |
| 16 | 17322113500591 |
| 17 | 116085219651667 |
| 18 | 777952310560487 |
| 19 | 5213495734620075 |
| 20 | 34938565521219551 |