I’d call it 0, but then I’m prone to zero-based indexing. I’d also call it wrong because 6 only appears there if you round up. That digit should be a 5.
f(1) = 0 (3; 3 props)
f(2) = 0 (31; 2 props)
f(3) = 1 (141; 2 props)
f(4) = 12 (9793; 7 props)
f(5) = 8 (53589; 6 props)
f(6) > 50, I can’t be bothered to find it. I might explore this programmatically in the future.
—Rory