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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 6 |
| 4 | 21 |
| 5 | 59 |
| 6 | 239 |
| 7 | 760 |
| 8 | 2970 |
| 9 | 10060 |
| 10 | 38930 |
| 11 | 124735 |
| 12 | 503767 |
| 13 | 1986024 |
| 14 | 7059818 |
| 15 | 27806989 |
| 16 | 107739266 |
| 17 | 376458328 |
| 18 | 1421570461 |
| 19 | 5750402871 |
| 20 | 23095812036 |
| 21 | 89360066340 |
| 22 | 315720338715 |
| 23 | 1202284699132 |
| 24 | 5133364318360 |
| 25 | 20343420316531 |
| 26 | 74430884941912 |
| 27 | 279471388089807 |