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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 5 |
| 6 | 6 |
| 7 | 42 |
| 8 | 64 |
| 9 | 387 |
| 10 | 5480 |
| 11 | 10461 |
| 12 | 113256 |
| 13 | 507390 |
| 14 | 1071084 |
| 15 | 4882635 |
| 16 | 44984560 |
| 17 | 382362589 |
| 18 | 891350154 |
| 19 | 7469477771 |
| 20 | 33066211100 |
| 21 | 78673599501 |
| 22 | 649785780710 |
| 23 | 2884039365010 |
| 24 | 22986956007816 |
| 25 | 306912836483025 |
| 26 | 1361558306986280 |
| 27 | 3519406658042964 |