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 | 4 |
| 2 | 15 |
| 3 | 58 |
| 4 | 229 |
| 5 | 912 |
| 6 | 3643 |
| 7 | 14566 |
| 8 | 58257 |
| 9 | 233020 |
| 10 | 932071 |
| 11 | 3728274 |
| 12 | 14913085 |
| 13 | 59652328 |
| 14 | 238609299 |
| 15 | 954437182 |
| 16 | 3817748713 |
| 17 | 15270994836 |
| 18 | 61083979327 |
| 19 | 244335917290 |
| 20 | 977343669141 |
| 21 | 3909374676544 |
| 22 | 15637498706155 |
| 23 | 62549994824598 |