OFFSET
1,2
COMMENTS
If integer-sided triangle has integer area, area is divisible by 6.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
PROG
(PARI) a(n)=sum(z=sqrtint(sqrtint(192*n^2)-1)+1, sqrtint(9*(64*n^2+5)\20), sum(y=z\2+1, z, my(t=(y*z)^2-(12*n)^2, x); if(issquare(t, &t), (issquare(y^2+z^2-2*t, &x) && x<=y) + (t && issquare(y^2+z^2+2*t, &x) && x<=y), 0))) \\ Charles R Greathouse IV, Jun 27 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved