# A076510 (b-file synthesized from sequence entry) 1 3 2 6 3 18 4 72 5 144 6 432 7 1728 8 3456 9 10368 10 41472 11 82944 12 248832 13 995328 14 1990656 15 5971968 16 23887872 17 47775744 18 143327232 19 573308928 20 1146617856 21 3439853568 22 13759414272 23 27518828544 24 82556485632 25 330225942528 26 660451885056