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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 21 |
| 6 | 57 |
| 7 | 162 |
| 8 | 479 |
| 9 | 1458 |
| 10 | 4528 |
| 11 | 14259 |
| 12 | 45349 |
| 13 | 145289 |
| 14 | 468121 |
| 15 | 1515128 |
| 16 | 4922145 |
| 17 | 16040310 |
| 18 | 52411294 |
| 19 | 171646085 |
| 20 | 563266323 |
| 21 | 1851661113 |
| 22 | 6096654978 |
| 23 | 20101681834 |
| 24 | 66362538332 |
| 25 | 219336702948 |
| 26 | 725692113292 |
| 27 | 2403295565913 |
| 28 | 7966021263923 |
| 29 | 26425616887971 |