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A152616
Numbers k such that exactly three subsets of proper divisors of k sum to k.
1
30, 40, 54, 350, 380, 414, 500, 532, 544, 558, 608, 620, 644, 666, 726, 740, 1372, 2002, 2190, 2368, 2370, 2490, 2624, 2670, 2910, 3030, 3090, 3162, 3210, 3250, 3270, 3390, 3410, 3430, 3810, 3880, 3930, 4040, 4110, 4120, 4170, 4280, 4360, 4470, 4520, 4530
OFFSET
1,1
COMMENTS
Or numbers k such that A065205(k) = 3.
LINKS
EXAMPLE
The proper divisors of 30 = {1,2,3,5,6,10,15} and 30 = 5+10+15 = 2+3+10+15 = 1+3+5+6+15.
MATHEMATICA
seqQ[n_] := Module[{d = Most[Divisors[n]]}, SeriesCoefficient[Series[Product[1 + x^d[[i]], {i, Length[d]}], {x, 0, n}], n] == 3]; Select[Range[1000], seqQ[#] &] (* Amiram Eldar, Jan 13 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Oct 29 2009
STATUS
approved