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Numbers that are both unitary and nonunitary Zumkeller numbers.
0

%I #4 May 25 2020 09:27:31

%S 150,294,630,726,750,840,1014,1050,1470,1650,1734,1890,1950,2058,2166,

%T 2550,2850,2940,2970,3174,3234,3450,3510,3630,3750,3822,4350,4410,

%U 4650,4998,5046,5070,5082,5250,5550,5586,5670,5766,6150,6450,6762,6930,7050,7098,7260

%N Numbers that are both unitary and nonunitary Zumkeller numbers.

%e 150 is a term since its unitary divisors, {1, 2, 3, 6, 25, 50, 75, 150} can be partitioned in two disjoint sets of equal sum: 1 + 2 + 3 + 25 + 50 + 75 = 6 + 150, and so are its nonunitary divisors, {5, 10, 15, 30}: 5 + 10 + 15 = 30.

%t zumQ[n_] := Module[{d = Divisors[n], ud, nd, sumUd, sumNd, x},ud = Select[d, CoprimeQ[#, n/#] &]; nd = Complement[d, ud]; sumUd = Plus @@ ud; sumNd = Plus @@ nd; sumUd >= 2*n && sumNd > 0 && EvenQ[sumUd] && EvenQ[sumNd] && CoefficientList[Product[1 + x^i, {i, ud}], x][[1 + sumUd/2]] > 0 && CoefficientList[Product[1 + x^i, {i, nd}], x][[1 + sumNd/2]] > 0]; Select[Range[10000], zumQ]

%Y Intersection of A290466 and A335142.

%K nonn

%O 1,1

%A _Amiram Eldar_, May 25 2020