OFFSET
1,1
COMMENTS
EXAMPLE
The fourth quadruple is 56, 63, 88, 171, hence a(4) = 88.
PROG
(PARI) {m=1110; for(n=6, m, for(a=1, (n-3)\3, for(b=a+1, (n-a-1)\2, c=n-a-b; d=a*b*c%(a+b+c); if(c<d, if(a*b*d%(a+b+d)==c, if(a*c*d%(a+c+d)==b, if(b*c*d%(b+c+d)==a, print1(c, ", "))))))))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Mar 12 2004
STATUS
approved