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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 69 |
| 5 | 431 |
| 6 | 3103 |
| 7 | 25271 |
| 8 | 228945 |
| 9 | 2276803 |
| 10 | 24605811 |
| 11 | 286742831 |
| 12 | 3580459501 |
| 13 | 47647919385 |
| 14 | 672666093583 |
| 15 | 10033841676961 |
| 16 | 157592244804465 |
| 17 | 2598219867015235 |
| 18 | 44845197606105859 |
| 19 | 808362808229409743 |
| 20 | 15184641619260934701 |
| 21 | 296660002497701895445 |
| 22 | 6017229226892950754271 |