The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 15 |
| 5 | 19 |
| 6 | 72 |
| 7 | 91 |
| 8 | 345 |
| 9 | 436 |
| 10 | 1653 |
| 11 | 2089 |
| 12 | 7920 |
| 13 | 10009 |
| 14 | 37947 |
| 15 | 47956 |
| 16 | 181815 |
| 17 | 229771 |
| 18 | 871128 |
| 19 | 1100899 |
| 20 | 4173825 |
| 21 | 5274724 |
| 22 | 19997997 |
| 23 | 25272721 |
| 24 | 95816160 |
| 25 | 121088881 |
| 26 | 459082803 |
| 27 | 580171684 |
| 28 | 2199597855 |
| 29 | 2779769539 |
| 30 | 10538906472 |
[1,3,4,15,19,72,91,345,436,1653,2089,7920,10009, 37947,47956,181815,229771,871128,1100899,4173825, 5274724,19997997,25272721,95816160,121088881, 459082803,580171684,2199597855,2779769539, 10538906472] |