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A323304 Heinz numbers of integer partitions that cannot be arranged into a matrix with equal row-sums and equal column-sums. 4

%I #6 Jan 14 2019 18:25:47

%S 6,10,12,14,15,18,20,21,22,24,26,28,30,33,34,35,38,39,40,42,44,45,46,

%T 48,50,51,52,54,55,56,57,58,60,62,63,65,66,68,69,70,72,74,75,76,77,78,

%U 80,82,84,85,86,87,88,90,91,92,93,94,95,96,98,99,102,104,105

%N Heinz numbers of integer partitions that cannot be arranged into a matrix with equal row-sums and equal column-sums.

%C The first term of this sequence absent from A106543 is 144.

%C The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).

%H <a href="/index/He#Heinz">Index entries for sequences related to Heinz numbers</a>

%t primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];

%t facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];

%t ptnmats[n_]:=Union@@Permutations/@Select[Union@@(Tuples[Permutations/@#]&/@Map[primeMS,facs[n],{2}]),SameQ@@Length/@#&];

%t Select[Range[2,1000],Select[ptnmats[#],And[SameQ@@Total/@#,SameQ@@Total/@Transpose[#]]&]=={}&]

%Y Complement of A323306.

%Y Cf. A006052, A007016, A008480, A056239, A112798, A120733, A319056, A321719, A321721.

%Y Cf. A323300, A323302, A323305, A323347, A323348, A323349.

%K nonn

%O 1,1

%A _Gus Wiseman_, Jan 13 2019

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Last modified April 25 01:35 EDT 2024. Contains 371964 sequences. (Running on oeis4.)