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The number of caterpillars
Harary, Frank; Schwenk, Allen J.
1973
Citation:Harary, Frank, Schwenk, Allen J. (1973)."The number of caterpillars." Discrete Mathematics 6(4): 359-365. <http://hdl.handle.net/2027.42/33977>
Abstract: A caterpillar is a tree which metamorphoses into a path when its cocoon of endpoints is removed. The number of nonisomorphic caterpillars with n+4 points is 2n + 2[n/2]. This neat formula is proved in two ways: first, as a special case of an application of Polya's enumeration theorem which counts graphs with integer-weighted points; secondly, by an appropriate labeling of the lines of the caterpillar.