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A216370 Number of ABC triples with quality q > 1 and c < 10^n. 2
1, 6, 31, 120, 418, 1268, 3499, 8987, 22316, 51677, 116978, 252856, 528275, 1075319, 2131671, 4119410, 7801334, 14482059 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

Dorian Goldfeld, Beyond the last theorem, Math Horizons, 1996 (September), pp. 26-34.

Richard K. Guy, Unsolved Problems in Number Theory, Springer-Verlag, 2004, ISBN 0-387-20860-7.

Carl Pomerance, Computational Number Theory, The Princeton Companion to Mathematics, Princeton University Press, 2008, pp. 361-362.

LINKS

Table of n, a(n) for n=1..18.

Jordan Ellenberg, Mochizuki on ABC

Reken Mee met ABC, Synthese resultaten, (Dutch), 2011

Wikipedia, abc conjecture

EXAMPLE

a(2) = 6 because there are 6 (a,b,c) triples with c < 10^2 and q > 1. Those triples are {1,8,9}, {1,48,49}, {1,63,64}, {1,80,81}, {5,27,32}, and {32,49,81}.

MATHEMATICA

rad[n_] := Times @@ Transpose[FactorInteger[n]][[1]]; Table[t = {}; mx = 10^n; Do[c = a + b; If[c < mx && GCD[a, b] == 1 && Log[c] > Log[rad[a*b*c]], AppendTo[t, {a, b, c}]], {a, mx/2}, {b, a, mx - a}]; Length[t], {n, 3}] (* T. D. Noe, Sep 06 2012 *)

CROSSREFS

Cf. A007947, A120498, A130510, A130511, A130512.

Sequence in context: A337574 A166786 A003728 * A225425 A267890 A244199

Adjacent sequences:  A216367 A216368 A216369 * A216371 A216372 A216373

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Sep 05 2012

STATUS

approved

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Last modified October 26 20:44 EDT 2020. Contains 338027 sequences. (Running on oeis4.)