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) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 19 |
| 4 | 140 |
| 5 | 1090 |
| 6 | 8749 |
| 7 | 71604 |
| 8 | 593997 |
| 9 | 4976785 |
| 10 | 42016975 |
| 11 | 356879250 |
| 12 | 3046096983 |
| 13 | 26105109424 |
| 14 | 224485080580 |
| 15 | 1936029865870 |
| 16 | 16738879226139 |
| 17 | 145041018993018 |
| 18 | 1259189426140919 |
| 19 | 10950454909118725 |
| 20 | 95374995078513150 |
| 21 | 831822673255797630 |
| 22 | 7263789225782699928 |