OFFSET
1,1
LINKS
Kival Ngaokrajang, Illustration of the first three solutions
Eric Weisstein's World of Mathematics, Soddy Circles.
PROG
(PARI)
soddy(k) = {
s=[];
for(a=1, k,
for(b=1, a-1,
for(c=1, b-1,
if(issquare(a*b*c*(a+b+c), &t),
if(a*b*c % (a*b+a*c+b*c+2*t) == 0,
s=concat(s, a)
)
)
)
)
);
s
}
soddy(500)
CROSSREFS
KEYWORD
nonn
AUTHOR
Colin Barker, Apr 08 2015
STATUS
approved