A104649 - OEIS

A104649

Numerators (denominators are all 840) of x-coordinates of four points on the parabola y = x^2, x >= 0, at rational distances (distance between any two points is rational).

475, 551, 799, 3076

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OFFSET

0,1

LINKS

Table of n, a(n) for n=0..3.

FORMULA

The distance formula between points on the parabola y = x^2.

EXAMPLE

We need 6 Pythagorean triples such that the ratios of the sides satisfies

(a+d = b+f = c+e) where x1+x2 = a, x2+x3 = b, x1+x3 = c, x3+x4 = d

(45/28 + 3551/840 = 171/140 + 775/168 = 91/60 + 1209/280). Solve for x1,x2,... to get the sequence.

CROSSREFS

Sequence in context: A237679 A236776 A236636 * A165463 A252518 A365871

Adjacent sequences: A104646 A104647 A104648 * A104650 A104651 A104652

KEYWORD

nonn,full,fini

AUTHOR

T. Haj (t.haj(AT)sbcglobal.net), Apr 21 2005

STATUS

approved