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A186308 Number of lobsters with n nodes that are not caterpillars. 1


%S 0,0,0,0,1,3,11,33,95,260,696,1816,4659,11795,29520,73267,180485,

%T 442157,1077856,2617726,6336551,15299287,36857178,88635225,212829307,

%U 510416549,1222826994,2927083468,7001510693,16737477645

%N Number of lobsters with n nodes that are not caterpillars.

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Caterpillar_tree">Caterpillar tree</a>

%F a(n) = A130131(n) - (2^(n-4) + 2^[(n-4)/2]).

%e All the trees of order less than 7 are caterpillars. Only one tree with 7 nodes is a lobster and is not a caterpillar, so a(3)=a(4)=a(5)=a(6)=0, and a(7)=1.

%Y Cf. A000055, A130131.

%K nonn

%O 3,6

%A _Washington Bomfim_, Feb 23 2011

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Last modified May 26 04:43 EDT 2022. Contains 354074 sequences. (Running on oeis4.)