A179785 Values x for records of minima of the positive distance d between the seventh power of a positive integer x and the square of an integer y such that d = x^7 - y^2 (x <> k^2 and y <> k^7).

2, 3, 6, 8, 10, 14, 18, 20, 28, 30, 39, 55, 59, 88, 239, 255, 257, 374, 387, 477, 1136, 1221, 9104, 10959, 35962, 43783, 96569, 148544, 183163, 194933, 313592, 842163, 1254392, 1468637, 1506412, 2377393, 2407523, 4636475, 5756417, 6615968

Offset: 1

Author

Artur Jasinski, Jul 27 2010

Keywords

• nonn

Comments

Distance d is equal to 0 when x = k^2 and y = k^7.

For d values see A179784.

For y values see A179786.

Conjecture (Artur Jasinski): For any positive number x >= A179785(n), the distance d between the seventh power of x and the square of any y (such that x <> k^2 and y <> k^7) can't be less than A179784(n).

Crossrefs

Cf. A179107, A179108, A179109, A179386, A179387, A179388, A179407, A179408, A179784, A179786.

Programs

Mathematica

d = 7; max = 1000; vecd = Table[10^100, {n, 1, max}]; vecx = Table[10^100, {n, 1, max}]; vecy = Table[10^100, {n, 1, max}]; len = 1; Do[m = Floor[(n^d)^(1/2)]; k = n^d - m^2; If[k != 0, ile = 0; Do[If[vecd[[z]] < k, ile = ile + 1], {z, 1, len}]; len = ile + 1; vecd[[len]] = k; vecx[[len]] = n; vecy[[len]] = m], {n, 1, 10000000}]; dd = {}; xx = {}; yy = {}; Do[AppendTo[dd, vecd[[n]]]; AppendTo[xx, vecx[[n]]]; AppendTo[yy, vecy[[n]]], {n, 1, len}]; xx