s = 0 unseen = 1 seen(v) = bit test(s, v) see(v) = s = bit or(s, 2^v); while (seen(unseen), unseen++) other(pp,p) = { for (v=unseen, oo, if (!seen(v), if (gcd(pp,p)>1 || gcd(pp,v)>1 || gcd(p,v)>1, return (v); ); ); ); } { for (n=1, 10 000, see(v = if (n<=2, unseen, other(pp,p))); print (n " " v); [pp,p]=[p,v]; ); } quit