example.hs

import Data.List
import System.IO

{-
 - THE PROBLEM:
 - For every real number a>1a>1 is given the sequence gaga by:
 - ga(x)=1ga(x)=1 for x<ax<a
 - ga(x)=ga(x−1)+ga(x−a)ga(x)=ga(x−1)+ga(x−a) for x≥ax≥a
 - G(n)=gn√(n)G(n)=gn(n)
 - G(90)=7564511G(90)=7564511.
 -
 - Find ∑G(p)∑G(p) for pp prime and 10000000<p<1001000010000000<p<10010000
 - Give your answer modulo 1000000007.
 -}

ga :: Float -> Float -> Float
ga x a
    | x < a = 1
    | x >= a = (ga (x-1) a) + (ga (x-a) a)
    | otherwise = 0

second :: Float -> Float
second n = ga n (sqrt n)

test = second 90

list = [10000000..10010000]
mapList = map second list
solution = mod (ceiling (product mapList)) 1000000007

--solution = (product (map second ) `mod` 1000000007