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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 21 |
| 6 | 86 |
| 7 | 346 |
| 8 | 1386 |
| 9 | 5547 |
| 10 | 22191 |
| 11 | 88767 |
| 12 | 355072 |
| 13 | 1420292 |
| 14 | 5681172 |
| 15 | 22724693 |
| 16 | 90898777 |
| 17 | 363595113 |
| 18 | 1454380458 |
| 19 | 5817521838 |
| 20 | 23270087358 |
| 21 | 93080349439 |
| 22 | 372321397763 |
| 23 | 1489285591059 |
| 24 | 5957142364244 |
| 25 | 23828569456984 |
| 26 | 95314277827944 |
| 27 | 381257111311785 |