|
%I #10 Jan 13 2020 09:34:17
%S 12,18,42,56,66,100,176,196,208,348,372,444,460,492,516,550,564,580,
%T 636,708,732,736,738,774,804,812,820,846,852,868,876,928,948,954,968,
%U 992,996,1036,1062,1068,1098,1148,1164,1204,1206,1212,1236,1278,1284,1308
%N Numbers k such that exactly two subsets of proper divisors of k sum to k.
%H Amiram Eldar, <a href="/A152615/b152615.txt">Table of n, a(n) for n = 1..2500</a>
%e k = 12: proper divisors of 12 = {1,2,3,4,6} and 12 = 2 + 4 + 6 = 1 + 2 + 3 + 6.
%t 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 *)
%Y Cf. A064771, A065205, A065235.
%K nonn
%O 1,1
%A _Zak Seidov_, Oct 29 2009
|
