A070200 - OEIS

%I #10 Dec 22 2017 18:55:40

%S 0,0,1,0,1,1,0,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,0,1,1,1,1,1,1,

%T 1,1,1,1,2,0,1,1,1,1,1,1,2,1,1,1,1,1,2,2,0,1,1,1,1,1,1,2,2,2,1,1,1,2,

%U 1,2,2,2,0,1,1,1,1,2,1,2,2,2,2,2,1,1,1,2,1,2

%N Inradii of integer triangles [A070080(n), A070081(n), A070082(n)], rounded values.

%C Triangles [A070080(A070209(n)), A070081(A070209(n)), A070082(A070209(n))] have integer inradii = a(A070209(k))= A070210(k).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Incircle.html">Incircle</a>.

%H R. Zumkeller, <a href="/A070080/a070080.txt">Integer-sided triangles</a>

%F a(n) = sqrt((s-u)*(s-v)*(s-w)/s), where u=A070080(n), v=A070081(n), w=A070082(n) and s=A070083(n)/2=(u+v+w)/2.

%e [A070080(25), A070081(25), A070082(25)] = [3,5,6] and s = A070083(25)/2 = (3+5+6)/2 = 7: a(25) = sqrt((s-3)*(s-5)*(s-6)/7) = sqrt((7-3)*(7-5)*(7-6)/7) = sqrt(4*2*1/7) = sqrt(8/7) = 1.069, rounded = 1.

%Y Cf. A070086.

%K nonn

%O 1,39

%A _Reinhard Zumkeller_, May 05 2002