# A051041 (b-file synthesized from sequence entry) 0 1 1 4 2 12 3 36 4 96 5 264 6 696 7 1848 8 4848 9 12768 10 33480 11 87936 12 230520 13 604608 14 1585128 15 4156392 16 10895952 17 28566216 18 74887056 19 196322976 20 514662960 21 1349208600 22 3536962584 23 9272217936 24 24307198464 25 63721617888 26 167046745992 27 437914664688 28 1147996820376 29 3009483583056 30 7889385389784 31 20682088837608 32 54218261608896