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Triangle read by rows giving Matula-Goebel numbers of planted achiral trees with n nodes.
5

%I #7 Jan 12 2017 15:59:42

%S 1,2,3,4,5,7,8,9,11,16,17,19,23,31,32,53,59,67,25,27,49,64,83,127,131,

%T 241,277,331,97,103,128,227,311,431,709,739,1523,1787,2221,81,121,256,

%U 289,361,509,563,719,1433,2063,3001,5381,5623,12763,15299,19577

%N Triangle read by rows giving Matula-Goebel numbers of planted achiral trees with n nodes.

%C An achiral tree is either (case 1) a single node or (case 2) a finite constant sequence (t,t,..,t) of achiral trees. Only in case 2 is an achiral tree considered to be a generalized Bethe tree (according to A214577).

%H E. Deutsch, <a href="http://arxiv.org/abs/1111.4288"> Rooted tree statistics from Matula numbers</a>, arXiv:1111.4288 [math.CO], 2011.

%e Triangle begins:

%e 1,

%e 2,

%e 3, 4,

%e 5, 7, 8,

%e 9, 11, 16, 17, 19,

%e 23, 31, 32, 53, 59, 67,

%e 25, 27, 49, 64, 83, 127, 131, 241, 277, 331.

%t nn=7;MGNumber[_[]]:=1;MGNumber[x:_[__]]:=If[Length[x]===1,Prime[MGNumber[x[[1]]]],Times@@Prime/@MGNumber/@x];

%t cits[n_]:=If[n===1,{1},Join@@Table[ConstantArray[#,(n-1)/d]&/@cits[d],{d,Divisors[n-1]}]];

%t Table[Sort[MGNumber/@(cits[n]/.(1->{}))],{n,nn}]

%Y Cf. A003238 (row lengths), A214577, A061773, A061775, A004111, A007097, A196545, A275870.

%K nonn,tabf

%O 1,2

%A _Gus Wiseman_, Jan 12 2017