Unrooted binary tree enumeration problem on unrooted binary trees is to count the number of trees with "n" labeled leaves and unlabeled internal nodes. An unrooted binary tree on "n" labeled leaves can be formed by connecting the "n"th leaf to a new node in the middle of any of the edges of an unrooted binary tree on "n" − 1 labeled leaves. There are 2"n" − 5 edges at which the "n"th node can be attached; therefore, the number of trees on "n" leaves is larger than the number of trees on "n" − 1 leaves by a factor of 2"n" −
Bibi-binary and the sum of −7 and 7 would give "0 0000"; this "two's complement" system thus needs only a single representation for the number zero. Bibi-binary The Bibi-binary system for numeric notation (in French système Bibi-binaire, or abbreviated "système Bibi") is a hexadecimal numeral system first described in 1968 by singer/mathematician Robert "Boby" Lapointe (1922–1972). At the time, it attracted the attention of André Lichnerowicz, then engaged in studies at the University of Lyon. It found some use in a variety of unforeseen applications: stochastic poetry, stochastic art, colour classification, aleatory music, architectural symbolism, etc. The notational system directly and