In 1750, Benjamin Franklin constructed the above semimagic square
having magic constant 260. Any half-row or half-column
in this square totals 130, and the four corners plus the middle total 260. In addition,
bent diagonals (such as 52-3-5-54-10-57-63-16) also total 260 (Madachy 1979, p. 87).
Describing his invention in 1771, Franklin stated, "I was at length tired with sitting there to hear debates, in which, as clerk, I could take no part, and which were often so unentertaining that I was induc'd to amuse myself with making magic squares or circles" (Franklin 1793).
semimagic square
having magic constant 260. Any half-row or half-column
in this square totals 130, and the four corners plus the middle total 260. In addition,
bent diagonals (such as 52-3-5-54-10-57-63-16) also total 260 (Madachy 1979, p. 87).
Franklin Squares."