\\ m = exponent of msb is(n, m) = { my (x=n); for (k=0, m, if (bittest(n, m-k)!=bittest(x, 0) || bittest(x, m-k)!=bittest(n, k), return (0) ); x=bitxor(x, x\2) ); return (1) } { for (w=1, oo, h=ceil(w/2); for (m=0, 2^h-1, x=n=m*2^(w-h); for (i=0, w-h-1, if (bittest(x,w-1-i), n+=2^i; ); x=bitxor(x,x\2); ); if (is(n, w-1), print (k++ " " n); ); ); if (k>=10 000, break; ); ); } quit