42nd Stern Diatomic Number

42nd Number in the Stern diatomic Number Sequence = 11

In general, the sequence is defined as: a(0) = 0, a(1) = 1; for n > 0: a(2*n) = a(n), a(2*n+1) = a(n) + a(n+1).

To understand this sequence, you might find it useful to read the Stern Diatomic (or Stern-Brocot sequence) tutorial over here.