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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 26 |
| 6 | 74 |
| 7 | 209 |
| 8 | 588 |
| 9 | 1651 |
| 10 | 4631 |
| 11 | 12983 |
| 12 | 36388 |
| 13 | 101972 |
| 14 | 285741 |
| 15 | 800660 |
| 16 | 2243445 |
| 17 | 6286059 |
| 18 | 17613241 |
| 19 | 49351342 |
| 20 | 138279586 |
| 21 | 387451077 |
| 22 | 1085614208 |
| 23 | 3041824015 |
| 24 | 8523002359 |
| 25 | 23880923183 |
| 26 | 66912861640 |
| 27 | 187485674652 |
| 28 | 525323190505 |
| 29 | 1471922876424 |
| 30 | 4124236259529 |