# A011951 (b-file synthesized from sequence entry) 5 2 6 3 7 9 8 16 9 39 10 75 11 165 12 318 13 672 14 1323 15 2703 16 5376 17 10880 18 21663 19 43605 20 87040 21 174564 22 348843 23 698709 24 1396680 25 2795518