big = 1 000 000 s = 0 S = Set([]) unseen = 1 seen(v) = if (v < big, bit test(s, v), set search(S, v)) see(v) = if (v < big, s = bit or(s, 2^v), S = set union(S, Set([v]))); while (seen(unseen), unseen++) other(pp,p) = { for (v=unseen, oo, if (!seen(v) && #Set([gcd(pp,p), gcd(p,v), gcd(v,pp)])==3, return (v); ); ); } for (n=1, 10 000, v=if (n<=3, n, other(pp,p)); see(v); print (n " " v); [pp,p]=[p,v]) quit