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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 7 |
| 4 | 20 |
| 5 | 45 |
| 6 | 112 |
| 7 | 267 |
| 8 | 648 |
| 9 | 1561 |
| 10 | 3772 |
| 11 | 9103 |
| 12 | 21980 |
| 13 | 53061 |
| 14 | 128104 |
| 15 | 309267 |
| 16 | 746640 |
| 17 | 1802545 |
| 18 | 4351732 |
| 19 | 10506007 |
| 20 | 25363748 |
| 21 | 61233501 |
| 22 | 147830752 |
| 23 | 356895003 |
| 24 | 861620760 |
| 25 | 2080136521 |
| 26 | 5021893804 |
| 27 | 12123924127 |
| 28 | 29269742060 |
| 29 | 70663408245 |