# A007465 (b-file synthesized from sequence entry) 0 1 1 6 2 30 3 128 4 486 5 1692 6 5512 7 17040 8 50496 9 144512 10 401664 11 1089024 12 2890240 13 7529472 14 19298304 15 48754688 16 121602048 17 299827200 18 731643904 19 1768685568 20 4239261696 21 10081796096 22 23805296640 23 55839817728 24 130187001856 25 301813727232 26 696036360192 27 1597358735360