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A280994
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Triangle read by rows giving Matula-Goebel numbers of planted achiral trees with n nodes.
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5
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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, 241, 277, 331, 97, 103, 128, 227, 311, 431, 709, 739, 1523, 1787, 2221, 81, 121, 256, 289, 361, 509, 563, 719, 1433, 2063, 3001, 5381, 5623, 12763, 15299, 19577
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OFFSET
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1,2
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COMMENTS
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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).
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LINKS
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EXAMPLE
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Triangle begins:
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, 241, 277, 331.
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MATHEMATICA
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nn=7; MGNumber[_[]]:=1; MGNumber[x:_[__]]:=If[Length[x]===1, Prime[MGNumber[x[[1]]]], Times@@Prime/@MGNumber/@x];
cits[n_]:=If[n===1, {1}, Join@@Table[ConstantArray[#, (n-1)/d]&/@cits[d], {d, Divisors[n-1]}]];
Table[Sort[MGNumber/@(cits[n]/.(1->{}))], {n, nn}]
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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