Source: Original.
Sums from 11 to 18: Sums from 9 to 16: 1 8 6 --> 15 3 1 8 --> 12 9 7 0 --> 16 9 2 0 --> 11 4 3 5 --> 12 4 6 5 --> 15 / | | | \ / | | | \ / | | | \ / | | | \ 17 14 18 11 13 14 16 9 13 10Interesting to note is that these two solutions are related - simply subtract each entry from 9, then flip the square left-to-right. - KD
with elements picks from the set (1,2,4,5) ; (1,1,1,1,2,2,4,4,5) we can form a sequential Magic square | 1 2 1 | 4 | 4 1 4 | 9 | 1 2 5 | 8 ---------------- 3 | 6 5 10 | 7