A257417 Values of n such that there are exactly 10 solutions to x^2 - y^2 = n with x > y >= 0.

960, 1344, 1728, 2112, 2240, 2496, 2592, 2835, 3240, 3264, 3520, 3648, 4160, 4416, 4455, 4536, 4928, 5265, 5440, 5568, 5824, 5952, 6080, 6144, 6237, 6885, 7104, 7128, 7360, 7371, 7616, 7695, 7872, 8000, 8256, 8424, 8512, 9024, 9152, 9280, 9315, 9639, 9920

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 200 terms from Colin Barker)

Example

960 is in the sequence because there are 10 solutions to x^2 - y^2 = 960, namely (x,y) = (31,1), (32,8), (34,14), (38,22), (46,34), (53,43), (64,56), (83,77), (122,118), (241,239).

Mathematica

nn = 10000;
t = Table[0, {nn}];
Do[n = x^2 - y^2; If[n <= nn, t[[n]]++], {x, nn}, {y, 0, x - 1}];
Position[t, 10] // Flatten (* Jean-François Alcover, Jun 18 2020, after T. D. Noe in A034178 *)

Prog

(PARI) is_A257417(n)={A034178(n)==10} \\ M. F. Hasler, Apr 22 2015

Crossrefs

Cf. A257408, A257409, A257410, A257411, A257412, A257413, A257414, A257415, A257416.

Cf. A034178.

Sequence in context: A108903 A167780 A316338 * A137491 A179672 A348523

Adjacent sequences: A257414 A257415 A257416 * A257418 A257419 A257420

Keyword

nonn

Author

Colin Barker, Apr 22 2015

Status

approved