BrainTwister #124: Odd sums

From New Scientist #3593, 2nd May 2026 [link] [link] There are five ways to write the number 5 as the sum of odd numbers: 1+1+1+1+1 3+1+1 1+3+1 1+1+3 5 (a) How many ways can the number 6 be written as the sum of odd numbers? (b) How many ways can the number 7 be written as [ ]