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A152615
Numbers k such that exactly two subsets of proper divisors of k sum to k.
2
12, 18, 42, 56, 66, 100, 176, 196, 208, 348, 372, 444, 460, 492, 516, 550, 564, 580, 636, 708, 732, 736, 738, 774, 804, 812, 820, 846, 852, 868, 876, 928, 948, 954, 968, 992, 996, 1036, 1062, 1068, 1098, 1148, 1164, 1204, 1206, 1212, 1236, 1278, 1284, 1308
OFFSET
1,1
LINKS
EXAMPLE
k = 12: proper divisors of 12 = {1,2,3,4,6} and 12 = 2 + 4 + 6 = 1 + 2 + 3 + 6.
MATHEMATICA
spdQ[n_]:=Module[{pds=Most[Divisors[n]]}, Length[Select[Subsets[ pds, Length[ pds]], Total[#] == n&]]==2]; Select[Range[1400], spdQ] (* Harvey P. Dale, Jan 23 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Oct 29 2009
STATUS
approved