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++) r(n) = my (v=0); while (n, v+=n%2; n\=2^valuation(n+(n%2),2)); v other(p) = { see(p); for (v=unseen, oo, if (!seen(v) && r(p+v) <= 2, return (v); ); ); } v=1; for (n=1, 10 000, print (n " " v); v=other(v)) quit