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FDH numbers of strict integer partitions with prime parts and prime length.
2

%I #5 Jun 29 2018 11:35:25

%S 12,21,28,33,44,57,75,76,77,84,100,123,132,133,141,164,175,183,188,

%T 209,228,231,244,249,275,287,291,300,308,329,332,363,388,399,417,427,

%U 451,453,475,484,492,507,517,525,532,556,564,581,591,604,627,671,676,679

%N FDH numbers of strict integer partitions with prime parts and prime length.

%C Let f(n) = A050376(n) be the n-th Fermi-Dirac prime. The FDH number of a strict integer partition (y_1,...,y_k) is f(y_1)*...*f(y_k).

%e Sequence of strict integer partitions with prime parts and prime length, preceded by their FDH numbers, begins:

%e 12: (3,2)

%e 21: (5,2)

%e 28: (5,3)

%e 33: (7,2)

%e 44: (7,3)

%e 57: (11,2)

%e 75: (13,2)

%e 76: (11,3)

%e 77: (7,5)

%e 84: (5,3,2)

%t nn=1000;

%t FDfactor[n_]:=If[n==1,{},Sort[Join@@Cases[FactorInteger[n],{p_,k_}:>Power[p,Cases[Position[IntegerDigits[k,2]//Reverse,1],{m_}->2^(m-1)]]]]];

%t FDprimeList=Array[FDfactor,nn,1,Union];FDrules=MapIndexed[(#1->#2[[1]])&,FDprimeList];

%t Select[Range[nn],And[PrimeQ[Length[FDfactor[#]]],And@@PrimeQ/@(FDfactor[#]/.FDrules)]&]

%Y Cf. A000586, A045450, A050376, A064547, A213925, A299755, A299757, A316185, A316265, A316267.

%K nonn

%O 1,1

%A _Gus Wiseman_, Jun 28 2018