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PROJECT EULER · #0422

Sequence of Points on a Hyperbola

Statement only · UnsolvedOriginal problem ↗

Let H be the hyperbola defined by the equation 12x2+7xy12y2=625.

Next, define X as the point (7,1). It can be seen that X is in H.

Now we define a sequence of points in H, {Pi:i1}, as:

  • P1=(13,61/4).
  • P2=(43/6,4).
  • For i>2, Pi is the unique point in H that is different from Pi1 and such that line PiPi1 is parallel to line Pi2X. It can be shown that Pi is well-defined, and that its coordinates are always rational.
0422_hyperbola.gif

You are given that P3=(19/2,229/24), P4=(1267/144,37/12) and P7=(17194218091/143327232,274748766781/1719926784).

Find Pn for n=1114 in the following format:
If Pn=(a/b,c/d) where the fractions are in lowest terms and the denominators are positive, then the answer is (a+b+c+d)mod1000000007.

For n=7, the answer would have been: 806236837.

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