OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..500
EXAMPLE
45 is in the sequence because there are 3 solutions to x^2 - y^2 = 45, namely (x,y) = (7,2),(9,6),(23,22).
MATHEMATICA
r[n_] := Reduce[x^2 - y^2 == n && x > y >= 0, {x, y}, Integers]; Reap[For[n = 1, n < 600, n++, rn = r[n]; If[rn[[0]] === Or && Length[rn] == 3, Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Apr 22 2015 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Colin Barker, Apr 22 2015
STATUS
approved