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A293188 Unitary pseudoperfect numbers: numbers that equal to the sum of a subset of their aliquot unitary divisors. 15
6, 30, 42, 60, 66, 78, 90, 102, 114, 138, 150, 174, 186, 210, 222, 246, 258, 282, 294, 318, 330, 354, 366, 390, 402, 420, 426, 438, 462, 474, 498, 510, 534, 546, 570, 582, 606, 618, 630, 642, 654, 660, 678, 690, 714, 726, 750, 762, 770, 780, 786, 798, 822 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Supersequence of A002827.
The nonsquarefree terms are 60, 90, 150, 294, 420, 630, 660, 726, 750, 780, 840, ...
LINKS
EXAMPLE
150 is in the sequence since its unitary aliquot divisors are 1, 2, 3, 6, 25, 50, 75 and 150 = 25 + 50 + 75.
MATHEMATICA
udiv[n_]:=Block[{d=Divisors[n]}, Select[d, GCD[#, n/#]==1&]]; a={}; n=0; While[Length[a]<100, n++; d=Most[udiv[n]]; c = SeriesCoefficient[ Series[ Product[1+x^d[[i]], {i, Length[d]} ], {x, 0, n}], n]; If[c>0, AppendTo[a, n]]]; a (* after T. D. Noe at A005835 *)
CROSSREFS
Sequence in context: A101937 A101939 A290466 * A080289 A175907 A114649
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 01 2017
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)