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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 12 |
| 5 | 38 |
| 6 | 143 |
| 7 | 490 |
| 8 | 1768 |
| 9 | 6268 |
| 10 | 22610 |
| 11 | 81620 |
| 12 | 297160 |
| 13 | 1086172 |
| 14 | 3991995 |
| 15 | 14731290 |
| 16 | 54587280 |
| 17 | 202992808 |
| 18 | 757398510 |
| 19 | 2834493948 |
| 20 | 10637507400 |
| 21 | 40023577524 |
| 22 | 150946230006 |
| 23 | 570534370692 |
| 24 | 2160865067312 |
| 25 | 8199710635816 |