project-euler/116_red_green_blue_tiles.py

#!/usr/bin/env python3

# Modified 115

def main(n):
    return p(2, n) + p(3, n) + p(4, n) - 3

def p(m, n, tbl=False):
    if n < m:
        return 1
    if tbl==False:
        tbl = []
    if n-m >= len(tbl):
        r = p(m, n-1, tbl) + p(m, n-m, tbl)
        tbl.append(r)
    return tbl[n-m]

print(main(50))