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A335145
Numbers that are both unitary and nonunitary Zumkeller numbers.
0
150, 294, 630, 726, 750, 840, 1014, 1050, 1470, 1650, 1734, 1890, 1950, 2058, 2166, 2550, 2850, 2940, 2970, 3174, 3234, 3450, 3510, 3630, 3750, 3822, 4350, 4410, 4650, 4998, 5046, 5070, 5082, 5250, 5550, 5586, 5670, 5766, 6150, 6450, 6762, 6930, 7050, 7098, 7260
OFFSET
1,1
EXAMPLE
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.
MATHEMATICA
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]
CROSSREFS
Intersection of A290466 and A335142.
Sequence in context: A184075 A207044 A292705 * A063829 A291959 A210643
KEYWORD
nonn
AUTHOR
Amiram Eldar, May 25 2020
STATUS
approved