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A295829
Unitary pseudoperfect numbers that equal to the sum of a subset of their aliquot unitary divisors in a single way.
4
6, 60, 78, 90, 102, 114, 138, 150, 174, 186, 222, 246, 258, 282, 294, 318, 354, 366, 402, 426, 438, 474, 498, 534, 582, 606, 618, 642, 654, 678, 726, 750, 762, 786, 822, 834, 894, 906, 942, 978, 1002, 1014, 1038, 1074, 1086, 1146, 1158, 1182, 1194, 1266, 1338
OFFSET
1,1
COMMENTS
The unitary version of A064771.
It appears that most of the terms are divisible by 3. Terms that are not divisible by 3 are 3770, 5530, 7210, 7630, ... - Michel Marcus, Dec 15 2017
The least odd term is 442365. - Amiram Eldar, Jun 10 2020
LINKS
EXAMPLE
150 is in the sequence since its aliquot unitary divisors are 1, 2, 3, 6, 25, 50, 75 and there is only one subset whose sum is 150: {25, 50, 75}.
MATHEMATICA
ud[n_] := Block[{d = Divisors[n]}, Select[d, GCD[#, n/#] == 1 &]];
a = {}; n = 0; While[Length[a] < 100, n++; d = Most[ud[n]];
c = SeriesCoefficient[Series[Product[1 + x^d[[i]], {i, Length[d]}], {x, 0, n}], n]; If[c ==1, AppendTo[a, n]]]; a
CROSSREFS
Sequence in context: A295830 A335937 A136937 * A074452 A168618 A185288
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 28 2017
STATUS
approved