! Copyright (c) 2009 Aaron Schaefer.
! See http://factorcode.org/license.txt for BSD license.
-USING: fry kernel math math.primes math.ranges project-euler.common sequences ;
+USING: kernel math math.primes project-euler.common ranges
+sequences ;
IN: project-euler.058
! http://projecteuler.net/index.php?section=problems&id=58
! (n-2)² + 4(n-1) = odd squares, no need to calculate
: prime-corners ( n -- m )
- 3 [1,b] swap '[ _ [ 1 - * ] keep 2 - sq + prime? ] count ;
+ 3 [1..b] swap '[ _ [ 1 - * ] keep 2 - sq + prime? ] count ;
: total-corners ( n -- m )
1 - 2 * ; foldable