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A173348 Numbers x such that 0 < |x^7 - y^2| < x^(5/2) for some number y. 32
12, 93, 239, 4896, 4904, 6546, 7806, 9104, 20542, 35962, 43783, 96569, 616400, 635331, 842163, 7888432 (list; graph; refs; listen; history; text; internal format)



Beukers and Stewart conjecture that for coprime integers n and m with n > m >= 2, and for any c > 0, the inequality 0 < |x^n - y^m| < c*X^(1-1/n-1/m) is true for infinitely many positive integers x and y, where X = max(x^n,y^m). They compute such x for 34 pairs (n,m). Given x, it is easy to compute y = round(x^(n/m)). Their tables have been extended to include all terms < 10^7 (or higher to obtain more terms).


Table of n, a(n) for n=1..16.

F. Beukers and C. L. Stewart, Neighboring powers, J. Number Theory, 130 (2010), 660-679.


Solutions[n_, m_, lim_] := Module[{x, y, t={}, pow=n*(1-1/m-1/n)}, Do[y=Round[x^(n/m)]; If[0 < Abs[x^n-y^m]<x^pow, AppendTo[t, x]], {x, lim}]; t]; Solutions[7, 2, 10^7]


Cf. A078933 (m=2, n=3, Hall's conjecture)

Cf. A116884 (m=2, n=5)

Cf. A173348 (m=2, n=7)

Cf. A173349 (m=2, n=9)

Cf. A173350 (m=2, n=11)

Cf. A173351 (m=3, n=4)

Cf. A173352 (m=3, n=5)

Cf. A173353 (m=3, n=7)

Cf. A173354 (m=3, n=8)

Cf. A173355 (m=3, n=10)

Cf. A173356 (m=3, n=11)

Cf. A173357 (m=4, n=5)

Cf. A173358 (m=4, n=7)

Cf. A173359 (m=4, n=9)

Cf. A173360 (m=4, n=11)

Cf. A173361 (m=5, n=6)

Cf. A173362 (m=5, n=7)

Cf. A173363 (m=5, n=8)

Cf. A173364 (m=5, n=9)

Cf. A173365 (m=5, n=11)

Cf. A173366 (m=5, n=12)

Cf. A173367 (m=6, n=7)

Cf. A173368 (m=6, n=11)

Cf. A173369 (m=7, n=8)

Cf. A173370 (m=7, n=9)

Cf. A173371 (m=7, n=10)

Cf. A173372 (m=7, n=11)

Cf. A173373 (m=7, n=12)

Cf. A173374 (m=8, n=9)

Cf. A173375 (m=8, n=11)

Cf. A173376 (m=9, n=10)

Cf. A173377 (m=9, n=11)

Cf. A173378 (m=10, n=11)

Cf. A173379 (m=11, n=12)

Sequence in context: A221291 A044263 A044644 * A294449 A073913 A057410

Adjacent sequences:  A173345 A173346 A173347 * A173349 A173350 A173351




T. D. Noe, Feb 22 2010



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Last modified December 14 05:17 EST 2018. Contains 318090 sequences. (Running on oeis4.)