Question 1022015
P = penny, N = nickel, D = dime, Q = quarter


1 coin: P, N, D, Q
values: 1, 5, 10, 25


2 coins: PN, PD, PQ, ND, NQ, DQ
values: 6, 11, 26, 15, 30, 45


3 coins: PND, PNQ, PDQ, NDQ
values: 16, 31, 36, 50 (omit the last one)


unique total amounts: 13