> with(linalg):with(numtheory):
Warning, the protected names norm and trace have been redefined and unprotected

Warning, the protected name order has been redefined and unprotected


 
> carmichael:=proc(n::integer)::Boolean;
> local i,l::integer, F::list;        
> if isprime(n) then return(false); fi:
> F:=ifactors(n)[2]:
> l:=linalg[rowdim](F):                                                    
> for i from 1 to l do  
>     if (F[i][2]>1) or igcd(F[i][1]-1,n-1)<>F[i][1]-1 then 
>        return(false);
>     fi
> od;
> return(true);
> end proc:
> carmichael2:=proc(N::integer)::integer;    
> local k::integer;    
> k:=N;
> while carmichael(k)=false do   
> k:=k-1;
> od;
> return(k);
> end proc: 
> carmichael2(2^(16));

                                63973