OFFSET
1,1
COMMENTS
There are no further terms.
For a(10)=672, there are 2 solutions: (28,60,80), (20,70,78).
For a(12)=840, there are 3 solutions: (35,73,102), (25,84,101), (21,89,100).
EXAMPLE
The areas 336,360,384,432,456, ... pertain respectively to triangles with sides (26,28,30), (25,29,36), (24,32,40), (30,30,48), (25,38,51), ..., equal 4 times their perimeter 84,90,96,108,114,...
MATHEMATICA
f[a_, b_, c_] := Block[{P = Total[{a, b, c}]/2}, Sqrt[P (P - a) (P - b) (P - c)]]; Sort@ Map[f @@ # &, Select[Union@ Map[Sort, Tuples[Range@ 200, {3}]], f @@ # == 4 Total@ # &] ] (* Michael De Vlieger, Jul 03 2017 *)
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Zhining Yang, Jun 28 2017
STATUS
approved