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A133475 Integers n such that n^3 + n^2 - 9*n + 16 is a square. 0
-4, -3, -1, 0, 1, 3, 5, 11, 15, 28, 47, 55, 81, 549, 1799, 8361 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The set of x values of integral points on the elliptic curve y^2 = x^3 + x^2 - 9*x + 16.

LINKS

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

EXAMPLE

0^3 + (-5)^2 + (-9) = 4^2, 1^3 + (-4)^2 + (-8) = 3^2, 3^3 + (-2)^2 + (-6) = 5^2

MATHEMATICA

ok[x_] := Reduce[{y^2 == x^3 + x^2 - 9*x + 16, y >= 0}, y, Integers] =!= False; Select[Table[x, {x, -4, 10000}], ok ] (* Jean-Fran├žois Alcover, Sep 07 2011 *)

PROG

(MAGMA) P<n> := PolynomialRing(Integers()); {x: x in Sort([ p[1] : p in IntegralPoints(EllipticCurve(n^3 + n^2 - 9*n + 16)) ])};

(Sage) EllipticCurve([0, 1, 0, -9, 16]).integral_points()

(PARI) is(n)=issquare(n^3+n^2-9*n+16) \\ Charles R Greathouse IV, Sep 06 2016

CROSSREFS

Cf. A117950, A132411, A132414, A002522, A028872.

Sequence in context: A144161 A054669 A131027 * A242106 A021236 A136590

Adjacent sequences:  A133472 A133473 A133474 * A133476 A133477 A133478

KEYWORD

sign,full,fini

AUTHOR

Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Nov 29 2007

EXTENSIONS

Edited by Max Alekseyev, Nov 13 2009

STATUS

approved

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Last modified May 30 00:42 EDT 2017. Contains 287304 sequences.