1,1

Colin Barker, Table of n, a(n) for n = 1..750

11 is in the sequence because the only solution to x^2 + 4xy + y^2 = 121 with 0 < x < y is (x,y) = (4,5).

Cf. A232437, A084645, A254063, A254064.

Sequence in context: A330975 A351841 A257864 * A274243 A192931 A002367

Adjacent sequences: A248596 A248597 A248598 * A248600 A248601 A248602

nonn

Colin Barker, Jan 21 2015

approved