Number of 2n-bead black-white reversible strings with n black beads.
1, 1, 4, 10, 38, 126, 472, 1716, 6470, 24310, 92504, 352716, 1352540, 5200300
1 seqfan posts
Thu Mar 12 16:47:23 CET 2009 [seqfan] Do the numbers of A032123 always occur exactly five times in Losanitsch's triangle?