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 | 9 |
| 2 | 51 |
| 3 | 234 |
| 4 | 951 |
| 5 | 3573 |
| 6 | 12707 |
| 7 | 43398 |
| 8 | 143682 |
| 9 | 464148 |
| 10 | 1469778 |
| 11 | 4578102 |
| 12 | 14063653 |
| 13 | 42695127 |
| 14 | 128301453 |
| 15 | 382144446 |
| 16 | 1129360689 |
| 17 | 3314619171 |
| 18 | 9668400839 |
| 19 | 28045947996 |
| 20 | 80949547380 |
| 21 | 232589050920 |
| 22 | 665532883380 |
| 23 | 1897176603420 |
| 24 | 5389368930505 |
| 25 | 15260830474869 |
| 26 | 43085718922071 |
| 27 | 121310066722194 |
| 28 | 340684392838971 |
| 29 | 954497114903169 |