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A093687
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Numbers k such that the total number of 1's in the binary expansion of all the divisors of k sets a new record.
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6
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1, 2, 3, 6, 12, 18, 24, 30, 60, 90, 120, 180, 252, 360, 420, 504, 540, 630, 756, 840, 1080, 1260, 1980, 2520, 3780, 5040, 6300, 7560, 12600, 13860, 15120, 21420, 25200, 27720, 32760, 41580, 42840, 49140, 55440, 65520, 81900, 83160, 98280, 128520, 138600
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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a[n_] := Plus @@ DigitCount[Divisors[n], 2, 1]; am = -1; c = 0; seq={}; Do[a1 = a[n]; If[a1 > am, am = a1; c++; AppendTo[seq, n]], {n, 1, 10^4}]; seq (* Amiram Eldar, Dec 17 2019 *)
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PROG
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(Python) # uses imports and definitions in A093653
from itertools import count, islice
def agen(r=0): yield from ((m, r:=fm)[0] for m in count(1) if (fm:=f(m))>r)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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