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 | 18 |
| 2 | 84 |
| 3 | 393 |
| 4 | 1830 |
| 5 | 8433 |
| 6 | 38376 |
| 7 | 171957 |
| 8 | 757362 |
| 9 | 3271533 |
| 10 | 13849980 |
| 11 | 57396693 |
| 12 | 233039058 |
| 13 | 927277245 |
| 14 | 3624209748 |
| 15 | 13934877933 |
| 16 | 52843565490 |
| 17 | 197989340133 |
| 18 | 734212702164 |
| 19 | 2698456656933 |
| 20 | 9837838481154 |
| 21 | 35609804891973 |
| 22 | 128026118332596 |
| 23 | 457386991178451 |