OFFSET
1,1
COMMENTS
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = a^2 + b^2, a and integers, 0 < a < b and gcd(a,b) = 1 in exactly two ways. These representations of a(n) are denoted by two different pairs (a,b).
EXAMPLE
n=1, 65: (1, 8), (4, 7),
n=2, 85: (2, 9), (6, 7),
n=3, 130: (3, 11), (7, 9),
n=4, 145: (1, 12), (8, 9),
n=5, 170: (1, 13), (7, 11),
n=6, 185: (4, 13), (8, 11),
n=7, 205: (3, 14), (6, 13),
n=8, 221: (5, 14), (10, 11),
n=9, 265: (3, 16), (11, 12),
n=10, 290: (1, 17), (11, 13).
MATHEMATICA
nn = 35; t = Sort[Select[Flatten[Table[If[GCD[a, b] == 1, a^2 + b^2, 0], {a, nn}, {b, a, nn}]], 0 < # <= nn^2 &]]; Transpose[Select[Tally[t], #[[2]] == 2 &]][[1]] (* T. D. Noe, Apr 20 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wolfdieter Lang, Apr 18 2013
STATUS
approved