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 A208770 Areas of triangle ABC, if it can be split by two straight lines through A and B, into 4 parts all with integer areas. 0

%I

%S 6,12,15,18,20,21,24,28,30,35,36,40,42,44,45,48,52,54,56,60,63,65,66,

%T 70,72,75,77,78,80,84,85,88,90,91,95,96,99,100,104,105,108,110,112,

%U 117,119,120

%N Areas of triangle ABC, if it can be split by two straight lines through A and B, into 4 parts all with integer areas.

%F n = a+b+c+d, if d = b*c*(2*a+b+c)/(a^2-b*c) is positive integer.

%e For n=6, some triangle with that area can be divided by 2 straight lines through A and B, into 4 parts with areas (2,1,1,2) or with areas (3,1,1,1). A triangle with area 12 can be divided into parts (2,1,2,7), (3,1,3,5), (4,2,2,4) and (6,2,2,2). Triangles with area 13 or 14 cannot be divided in this way.

%K nonn,more

%O 1,1

%A _Dragan Krejakovic_, Mar 01 2012

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Last modified June 18 12:24 EDT 2021. Contains 345107 sequences. (Running on oeis4.)