Least k for which the linear difference equation that solves x^2 + (x+k)^2 = y^2 has order 4n-1.

1, 7, 49, 343, 119, 16807, 117649, 833, 5764801, 40353607, 5831

1

Terms 13 and 14 are 14161 and 2737, respectively.

T. D. Noe, Plot of 11 terms

Cf. S000648.

nonn,hard,more

T. D. Noe, Jun 04 2015