https://twitter.com/pickover/status/1333418883437486080

attacked.py

# Maximum unattacked squares

def attacked_from_square(r, c):
    attacked = set([])
    for i in range(5):
        attacked.add((r,i))
        attacked.add((i,c))
        if 0<=r+i<5 and 0<=c+i<5:
            attacked.add((r+i,c+i))
        if 0<=r+i<5 and 0<=c-i<5:
            attacked.add((r+i,c-i))
        if 0<=r-i<5 and 0<=c+i<5:
            attacked.add((r-i,c+i))
        if 0<=r-i<5 and 0<=c-i<5:
            attacked.add((r-i,c-i))
    return attacked

def count_unattacked(board):
    attacked = set([])
    for i in board:
        attacked.update(attacked_from_square(i//5, i%5))
    return 25 - len(attacked)


import itertools
max_ = 0
for board in itertools.combinations(range(25), 5):
    new = count_unattacked(board)
    if new > max_:
        max_ = new
        print(f"{max_}: {board}")