Project Euler 318: Project Euler 318: Counting the number of consecutive nines at the beginning of the fractional part of (√p+√q)²ⁿ

Project Euler 318: Consider the real number √2+√3.

When we calculate the even powers of √2+√3
we get:

(√2+√3)² = 9.898979485566356…
(√2+√3)⁴ = 97.98979485566356…
(√2+√3)⁶ = 969.998969071069263…
(√2+√3)⁸ = 9601.99989585502907…
(√2+√3)¹⁰ = 95049.999989479221…
(√2+√3)¹² = 940897.9999989371855…
(√2+√3)¹⁴ = 9313929.99999989263…
(√2+√3)¹⁶ = 92198401.99999998915…

It looks like that the number of consecutive nines at the beginning of the fractional part of these powers is non-decreasing.

In fact it can be proven that the fractional part of (√2+√3)²ⁿ approaches 1 for large n.

Consider all real numbers of the form √p+√q with p and q positive integers and p<q, such that the fractional part
of (√p+√q)²ⁿ approaches 1 for large n.

Let C(p,q,n) be the number of consecutive nines at the beginning of the fractional part of
(√p+√q)²ⁿ.

Let N(p,q) be the minimal value of n such that C(p,q,n) ≥ 2011.

Find ∑N(p,q) for p+q ≤ 2011.

Project Euler 318 Solution

Afterthoughts

No afterthoughts yet.