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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 23 |
| 6 | 82 |
| 7 | 300 |
| 8 | 1129 |
| 9 | 4334 |
| 10 | 16914 |
| 11 | 66899 |
| 12 | 267586 |
| 13 | 1080516 |
| 14 | 4398850 |
| 15 | 18035084 |
| 16 | 74402361 |
| 17 | 308624282 |
| 18 | 1286428765 |
| 19 | 5385578256 |
| 20 | 22635057148 |
| 21 | 95471113565 |
| 22 | 403983783772 |
| 23 | 1714494024947 |
| 24 | 7295949019114 |
| 25 | 31124885587680 |
| 26 | 133085594104222 |
| 27 | 570266646942488 |