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) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 12 |
| 7 | 43 |
| 8 | 143 |
| 9 | 504 |
| 10 | 1768 |
| 11 | 6310 |
| 12 | 22610 |
| 13 | 81752 |
| 14 | 297160 |
| 15 | 1086601 |
| 16 | 3991995 |
| 17 | 14732720 |
| 18 | 54587280 |
| 19 | 202997670 |
| 20 | 757398510 |
| 21 | 2834510744 |
| 22 | 10637507400 |
| 23 | 40023636310 |
| 24 | 150946230006 |
| 25 | 570534578704 |
| 26 | 2160865067312 |
| 27 | 8199711378716 |
| 28 | 31170212479588 |
| 29 | 118686578956272 |