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 | 6 |
| 2 | 30 |
| 3 | 138 |
| 4 | 606 |
| 5 | 2610 |
| 6 | 11070 |
| 7 | 46386 |
| 8 | 192606 |
| 9 | 793938 |
| 10 | 3253038 |
| 11 | 13261746 |
| 12 | 53832462 |
| 13 | 217707762 |
| 14 | 877594086 |
| 15 | 3527521794 |
| 16 | 14142930774 |
| 17 | 56574143754 |
| 18 | 225841103190 |
| 19 | 899866007610 |
| 20 | 3579435531846 |
| 21 | 14215941861138 |
| 22 | 56378805654510 |
| 23 | 223297285830858 |
| 24 | 883326046736814 |