OFFSET
1,1
COMMENTS
Four distinct positive integers the sum of any two of which is a square, two of the squares being equal.
Dunham calls them "Euler's fearsome foursome", but neglects to require that two of the sums be equal. Liu requires it and explains Euler's derivation.
REFERENCES
W. Dunham, Euler: The Master of Us All, MAA, 1999, p. 7.
L. Euler, Opera Omnia, vol. 5, pp. 337 - 339, supplement to Paper 796.
LINKS
Paul Liu, The Elementary Mathematical Works of Leonhard Euler (1707 - 1783), pp. 129-133.
EXAMPLE
If (A, B, C, D) = (18530, 38114, 45986, 65570), then A+D = B+C = 290^2, A+C = 254^2, C+D = 334^2, A+B = 238^2, and B+D = 322^2.
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Jonathan Sondow, Sep 12 2013
STATUS
approved