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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A299202 Moebius function of the multiorder of integer partitions indexed by their Heinz numbers.

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%I A299202 #15 Feb 23 2018 11:10:35
%S A299202 0,1,1,-1,1,-1,1,0,-1,-1,1,2,1,-1,-1,-1,1,1,1,1,-1,-1,1,-1,-1,-1,0,1,
%T A299202 1,3,1,0,-1,-1,-1,-1,1,-1,-1,-1,1,2,1,1,1,-1,1,0,-1,1,-1,1,1,-1,-1,-1,
%U A299202 -1,-1,1,-3,1,-1,2,0,-1,2,1,1,-1,3,1,2,1,-1,1,1,-1,2,1,1,-1,-1,1,-5,-1,-1,-1,-1,1,-4
%N A299202 Moebius function of the multiorder of integer partitions indexed by their Heinz numbers.
%C A299202 By convention, mu() = 0.
%C A299202 The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
%H A299202 Gus Wiseman, <a href="https://docs.google.com/document/d/1m0s6DGTBkDW9gvMuFmJHvy6oLGRAbQ7okAZcOPZawp0/pub">Comcategories and Multiorders</a>
%F A299202 mu(y) = Sum_{g(t)=y} (-1)^d(t), where the sum is over all enriched p-trees (A289501, A299203) whose multiset of leaves is the integer partition y, and d(t) is the number of non-leaf nodes in t.
%e A299202 Heinz number of (2,1,1) is 12, so mu(2,1,1) = a(12) = 2.
%t A299202 nn=120;
%t A299202 ptns=Table[If[n===1,{},Join@@Cases[FactorInteger[n]//Reverse,{p_,k_}:>Table[PrimePi[p],{k}]]],{n,nn}];
%t A299202 tris=Join@@Map[Tuples[IntegerPartitions/@#]&,ptns];
%t A299202 mu[y_]:=mu[y]=If[Length[y]===1,1,-Sum[Times@@mu/@t,{t,Select[tris,And[Length[#]>1,Sort[Join@@#,Greater]===y]&]}]];
%t A299202 mu/@ptns
%Y A299202 Cf. A000041, A063834, A112798, A196545, A273873, A281145, A289501, A290261, A296150, A299200, A299201, A299203.
%K A299202 sign
%O A299202 1,12
%A A299202 _Gus Wiseman_, Feb 05 2018