Problem 76 - Counting summations, by memoization

 - Find the number of 2 digit solutions, then 3 digit, etc. up to 100 digits
 - Number of N-digit solutions is sum of number of N-1-digit solutions for each valid first term
 - Memoization kicks in to cache the repeated queries
 - There is apparently an elegant formula/algorithm to solve this from the Forum - to be investigated!