%I #5 Mar 02 2020 18:53:35
%S 21,24,27,30,33,36,39,42,42,45,60,66,75,81,99,105,171,306
%N 2*a(n) are the perimeters of distinct triangles with integer sides i <= j <= k, whose area equals 2 times their perimeter. Terms occurring more than once belong to different triangles.
%C There are 18 integer-sided triangles with 2*area = perimeter, with terms 42 corresponding to a pair of such triangles with different sides.
%Y Equals A289218/2.
%Y Cf. A289219, A289220, A289221, A332879, A289253 (all merging terms for triangles with identical perimeters, but different sides).
%K nonn,fini,full
%O 1,1
%A _Hugo Pfoertner_, Mar 02 2020