define negdujella(k){ auto r,i,kk,z,g,count,kkover2 kk=k^2+1 kkover2=kk/2 r=sqroot(1,kk,0) count=0 for(i=0;i1 && x<=kkover2){ z=(x^2-1)/kk g=issquare(z+1) if(g>1 && g1){ print "counter-example\n" return(-1) } } return(count) } /* This uses the fact that X^2-(k^2+1)=-k^2 implies X^2-1=(k^2+1)(y^2-1). * Dujella's unicity conjecture is equivalent to there being at most one positive integer * solution satisfying 11 && x<=kkover2){ z=(x^2-1)/kk g=issquare(z+1) if(g>1 && g