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 | 4 |
| 1 | 9 |
| 2 | 21 |
| 3 | 49 |
| 4 | 115 |
| 5 | 270 |
| 6 | 634 |
| 7 | 1489 |
| 8 | 3498 |
| 9 | 8218 |
| 10 | 19307 |
| 11 | 45359 |
| 12 | 106565 |
| 13 | 250361 |
| 14 | 588192 |
| 15 | 1381884 |
| 16 | 3246565 |
| 17 | 7627402 |
| 18 | 17919636 |
| 19 | 42099965 |
| 20 | 98908653 |
| 21 | 232373629 |
| 22 | 545933059 |
| 23 | 1282602102 |
| 24 | 3013314774 |
| 25 | 7079409829 |
| 26 | 16632196530 |
| 27 | 39075285666 |
| 28 | 91802543767 |
| 29 | 215678705823 |