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 | 6 |
| 3 | 23 |
| 4 | 107 |
| 5 | 587 |
| 6 | 3725 |
| 7 | 26952 |
| 8 | 219756 |
| 9 | 1998951 |
| 10 | 20105485 |
| 11 | 221838905 |
| 12 | 2666280457 |
| 13 | 34689290378 |
| 14 | 485840964614 |
| 15 | 7288997427755 |
| 16 | 116634438986227 |
| 17 | 1982868327635663 |
| 18 | 35692311974248093 |
| 19 | 678159760252918824 |
| 20 | 13563246929216611852 |
| 21 | 284828660383365005643 |