`` The Recurrence operator annihilating a_r(n):=The number of ways of making change of n cents only using pennies, nickels, dimes, and quarter\ s where the person has r pockets the money can come from, is: 2 3 4 5 6 7 (-41 r - n) - r N - r N - r N - r N + (-5 - n - 47 r) N - 2 r N - 2 r N 8 9 10 11 12 13 14 - 2 r N - 2 r N - 22 r N - 2 r N - 2 r N - 2 r N - 2 r N - 15 16 17 18 19 20 21 22 r N - 2 r N - 2 r N - 2 r N - 2 r N - 22 r N - 2 r N - 2 r 22 23 24 25 26 27 28 N - 2 r N - 2 r N + (25 + n - 6 r) N - r N - r N - r N - r 29 30 N + (30 + n) N This took, 1.572, seconds