Problem of the Week 843

Sums of powers of two

How many ways can 90316 be written as

a + 2 b + 4 c + 8 d + 16 e + 32 f + ···

where the coefficients can be any of 0, 1, or 2?

Source: Sept/Oct 1997 Quantum

© Copyright 1997 Stan Wagon. Reproduced with permission.