# A084861 (b-file synthesized from sequence entry) 0 1 1 1 2 4 3 9 4 21 5 48 6 108 7 240 8 528 9 1152 10 2496 11 5376 12 11520 13 24576 14 52224 15 110592 16 233472 17 491520 18 1032192 19 2162688 20 4521984 21 9437184 22 19660800 23 40894464 24 84934656 25 176160768 26 364904448 27 754974720 28 1560281088 29 3221225472