OFFSET
1,2
COMMENTS
Radii shared by more than one triangle are not removed. The first occurrence is for squared radius 64/15 at positions n = 10 and n = 11.
FORMULA
Squared radius of circumcircle of triangle with sides a, b, c:
R^2 = (a*b*c)^2 / (16*s*(s - a)*(s - b)*(s - c)) with s = (a + b + c)/2.
EXAMPLE
The first terms b(n) = a(n)/A331228(n) correspond to the following triangles (i, j, k):
b(1) = 1/3: (1,1,1),
b(2) = 16/15: (1,2,2),
b(3) = 4/3: (2,2,2),
b(4) = 16/7: (2,2,3) (obtuse triangle excluded in A331222),
b(5) = 81/35: (1,3,3),
b(6) = 81/32: (2,3,3),
b(7) = 3/1: (3,3,3),
b(8) = 81/20: (3,3,4),
b(9) = 256/63: (1,4,4),
b(10) = 64/15: (2,3,4), (obtuse)
b(11) = 64/15: (2,4,4).
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Hugo Pfoertner, Jan 12 2020
STATUS
approved