Stream sharing in Hamming-number construction

The Hamming number stream merges its shared multiples by two, three and five. To emit its first $n$ values, each of the fixed number of mapped streams and merge nodes advances at most $n+O(1)$ positions. With lazy evaluation that shares each evaluated list cell, this takes $\Theta (n)$ comparisons and fixed-factor multiplications. The statement counts arithmetic operations, rather than bits: the growing exact integers make their bit-operation costs larger. Recomputing independent copies of the recursively defined stream loses this sharing argument.