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 | 1 |
| 3 | 0 |
| 4 | 6 |
| 5 | 21 |
| 6 | 114 |
| 7 | 597 |
| 8 | 3278 |
| 9 | 18420 |
| 10 | 105618 |
| 11 | 615331 |
| 12 | 3632352 |
| 13 | 21678975 |
| 14 | 130598887 |
| 15 | 793085742 |
| 16 | 4849791942 |
| 17 | 29838388707 |
| 18 | 184573315170 |
| 19 | 1147219365762 |
| 20 | 7161284719412 |
| 21 | 44876343104655 |
| 22 | 282206695488603 |
| 23 | 1780341161583746 |
| 24 | 11264338644455334 |
| 25 | 71461150894269030 |