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A067632
n(n+180) is a square.
1
-2116, -768, -500, -324, -240, -196, -192, -180, 0, 12, 16, 60, 144, 320, 588, 1936
OFFSET
0,1
COMMENTS
Rewrite it as s^2 - t^2 = 90^2 to see that there are only finitely many solutions.
REFERENCES
Albert H. Beiler, Recreations in the Theory of Numbers (2d ed. 1966), pp. 296, 317.
EXAMPLE
588 is included because 588 * (588 + 180) = 451584, the square root of which is 672.
MAPLE
isolve(n*(n+180)=m^2);
MATHEMATICA
Select[Range[-2200, 2200], IntegerQ[Sqrt[#(#+180)]]&] (* Harvey P. Dale, Jun 11 2019 *)
CROSSREFS
Sequence in context: A246808 A217439 A365240 * A236446 A077731 A077733
KEYWORD
sign,fini,full
AUTHOR
Harvey P. Dale, Feb 02 2002
STATUS
approved